Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 26, 2018	Jun. 30, 2017
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	OMER
Entity Registrant Name	OMEROS CORP
Entity Central Index Key	0001285819
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		48,285,978
Entity Public Float			$ 830,503,401

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,394	$ 2,224
Short-term investments	80,355	43,107
Receivables, net	17,144	12,037
Inventory	443	1,128
Prepaid expense	7,036	1,766
Total current assets	108,372	60,262
Property and equipment, net	2,121	1,181
Restricted investments	5,835	5,835
Total assets	116,328	67,278
Current liabilities:
Accounts payable	6,691	2,519
Accrued expenses	19,126	13,354
Current portion of lease financing obligations	490	198
Total current liabilities	26,307	16,071
Notes payable and lease financing obligations, net	84,117	79,512
Deferred rent	8,718	9,142
Commitments and contingencies (Note 8)
Shareholders’ deficit:
Preferred stock, par value $0.01 per share, 20,000,000 authorized and none issued at December 31, 2017 and 2016.	0	0
Common Stock, par value $0.01 per share, 150,000,000 shares authorized at December 31, 2017 and 2016; 48,211,226 and 43,819,133 issued and outstanding at December 31, 2017 and December 31, 2016, respectively.	482	438
Additional paid-in capital	520,072	432,002
Accumulated deficit	(523,368)	(469,887)
Total shareholders’ deficit	(2,814)	(37,447)
Total liabilities and shareholders’ deficit	$ 116,328	$ 67,278

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (USD per share)	$ 0.01	$ 0.01
Preferred stock, authorized shares	20,000,000	20,000,000
Preferred stock, Issued shares	0	0
Preferred stock, outstanding shares	0	0
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, authorized shares	150,000,000	150,000,000
Common stock, Issued shares	48,211,226	43,819,133
Common stock, outstanding shares	48,211,226	43,819,133

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Product sales, net	$ 64,826	$ 41,444	$ 13,264
Grant revenue	0	173	245
Total revenue	64,826	41,617	13,509
Costs and expenses:
Cost of product sales	1,078	1,412	1,041
Research and development	55,599	50,699	48,379
Selling, general and administrative	52,044	43,782	35,327
Total costs and expenses	108,721	95,893	84,747
Loss from operations	(43,895)	(54,276)	(71,238)
Interest expense	(11,030)	(7,819)	(3,573)
Other income	1,444	945	1,030
Loss on early extinguishment of debt	0	(5,595)	(1,315)
Net loss	(53,481)	(66,745)	(75,096)
Comprehensive loss	$ (53,481)	$ (66,745)	$ (75,096)
Basic and diluted net loss per share (in dollars per share)	$ (1.17)	$ (1.65)	$ (2.00)
Weighted-average shares used to compute basic and diluted net loss per share (in shares)	45,539,362	40,446,410	37,560,257

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	JonesTrading, ATM Agreement	Common Stock	Common Stock JonesTrading, ATM Agreement	Additional Paid-in Capital	Additional Paid-in Capital JonesTrading, ATM Agreement	Accumulated Deficit
Balance (in shares) at Dec. 31, 2014			34,185,464
Balance at Dec. 31, 2014	$ (42,654)		$ 342		$ 285,050		$ (328,046)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and pre-funded warrants, net of offering costs	79,076		$ 34		79,042
Issuance of common stock and pre-funded warrants, net of offering costs (shares)			3,444,831
Issuance of common stock upon exercise of warrants (shares)			133,240
Issuance of common stock upon exercise of warrants	1,436		$ 1		1,435
Issuance of common stock upon exercise of stock options for cash (in shares)			277,356
Issuance of common stock upon exercise of stock options	1,423		$ 3		1,420
Stock-based compensation	9,581				9,581
Net loss	(75,096)						(75,096)
Balance (in shares) at Dec. 31, 2015			38,040,891
Balance at Dec. 31, 2015	(26,234)		$ 380		376,528		(403,142)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and pre-funded warrants, net of offering costs	37,314	$ 725	$ 35	$ 1	37,279	$ 724
Issuance of common stock and pre-funded warrants, net of offering costs (shares)			3,478,260	64,565
Issuance of common stock upon exercise of warrants (shares)			749,250
Issuance of common stock upon exercise of warrants	7		$ 7		0
Issuance of common stock upon exercise of stock options for cash (in shares)			1,486,167
Issuance of common stock upon exercise of stock options	3,146		$ 15		3,131
Stock-based compensation	13,582				13,582
Warrants issued in connection with amendment to notes payable	758				758
Net loss	(66,745)						(66,745)
Balance (in shares) at Dec. 31, 2016			43,819,133
Balance at Dec. 31, 2016	(37,447)		$ 438		432,002		(469,887)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and pre-funded warrants, net of offering costs	$ 63,657		$ 30		63,627
Issuance of common stock and pre-funded warrants, net of offering costs (shares)			3,000,000
Issuance of common stock upon exercise of stock options for cash (in shares)	1,392,093		1,392,093
Issuance of common stock upon exercise of stock options	$ 11,769		$ 14		11,755
Stock-based compensation	12,688				12,688
Net loss	(53,481)						(53,481)
Balance (in shares) at Dec. 31, 2017			48,211,226
Balance at Dec. 31, 2017	$ (2,814)		$ 482		$ 520,072		$ (523,368)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net loss	$ (53,481,000)	$ (66,745,000)	$ (75,096,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	12,688,000	13,582,000	9,581,000
Non-cash interest expense	4,187,000	1,977,000	1,045,000
Depreciation and amortization	551,000	300,000	209,000
Loss on early extinguishment of debt	0	5,595,000	1,315,000
Warrant modification expense
Receivables	(5,107,000)	(5,520,000)	(6,125,000)
Inventory	685,000	(656,000)	96,000
Prepaid expenses	(5,270,000)	347,000	(586,000)
Accounts payable, accrued expenses and other	9,520,000	(384,000)	4,352,000
Net cash used in operating activities	(36,227,000)	(51,504,000)	(65,209,000)
Investing activities:
Purchases of property and equipment	(350,000)	(126,000)	(240,000)
Purchases of investments	(65,326,000)	(73,966,000)	(91,766,000)
Proceeds from the sale and maturities of investments	28,078,000	57,757,000	71,400,000
Net cash used in investing activities	(37,598,000)	(16,335,000)	(20,606,000)
Financing activities:
Proceeds from issuance of common stock and pre-funded warrants, net	63,657,000	38,039,000	79,076,000
Proceeds from borrowings under notes payable	0	100,000,000	50,000,000
Payments on notes payable and lease financing obligations	(431,000)	(70,137,000)	(32,000,000)
Payments on debt prepayment and extinguishment	0	(5,700,000)	(2,673,000)
Payments for debt issuance costs	0	(1,501,000)	(436,000)
Decrease (increase) in restricted investments	0	4,844,000	(10,000,000)
Proceeds upon exercise of stock options and warrants	11,769,000	3,153,000	2,859,000
Net cash provided by financing activities	74,995,000	68,698,000	86,826,000
Net increase in cash and cash equivalents	1,170,000	859,000	1,011,000
Cash and cash equivalents at beginning of period	2,224,000	1,365,000	354,000
Cash and cash equivalents at end of period	3,394,000	2,224,000	1,365,000
Supplemental cash flow information
Cash paid for interest	6,895,000	5,293,000	4,236,000
Conversion of accrued interest to notes payable	3,315,000	516,000	0
Property acquired under capital lease	1,141,000	404,000	137,000
Issuance of warrants in connection with amendment to notes payable	$ 0	$ 758,000	$ 0

Organization and Basis of Presentation

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Organization and Basis of Presentation

Organization

We are a commercial-stage biopharmaceutical company committed to discovering, developing and commercializing small-molecule and protein therapeutics for large-market as well as orphan indications targeting inflammation, complement-mediated diseases and disorders of the central nervous system. Our first drug product, OMIDRIA, is marketed in the United States (U.S.) for use during cataract surgery or intraocular lens replacement.

Basis of Presentation

Our consolidated financial statements include the financial position and results of operations of Omeros Corporation (Omeros) and our wholly owned subsidiaries. All inter-company transactions have been eliminated. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP). Certain prior year amounts in the statement of cash flows and the income tax footnote have been reclassified in the consolidated financial statements to conform to the current year presentation.

Segments

We operate in one segment. Management uses cash flow as the primary measure to manage our business and does not segment our business for internal reporting or decision-making.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant items subject to such estimates include revenue recognition, stock-based compensation expense and accruals for clinical trials, manufacturing of drug product and clinical drug supply and contingencies. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances; however, actual results could differ from these estimates.

Going Concern

On an interim and annual basis we are required to assess our ability to continue as a going concern for one year after the date the financial statements are issued using rules defined by ASC No. 205-40 - Going Concern (the Standard). As required by the Standard, management’s evaluation shall initially not take into consideration the potential mitigating effects of management’s plans that have not been fully implemented as of the date the financial statements are issued. In the second step of this evaluation, management’s assumptions and plans are derived according to restrictions and definitions in the Standard. As such, for purposes of this exercise, the following assumptions (which are discussed in further detail following this summary) were made:


•	No revenues from sales of OMIDRIA. We are unable at this time to predict accurately revenue from sales of OMIDRIA given the loss of CMS reimbursement and, therefore, no OMIDRIA revenues are included for this exercise. We are pursuing continued separate payment for OMIDRIA and, in the event that we are unsuccessful, we would implement in the near-term an alternative sales strategy for OMIDRIA;

•

No additional draws on our CRG debt facility. As disclosed in Note 7, we are in compliance with all covenants under our CRG Loan Agreement. On February 26, 2018, we amended our CRG Loan Agreement to extend our ability to borrow up to $45.0 million through May 20, 2018 subject only to customary closing conditions. However, given the existence of customary closing conditions, including a typical material adverse event clause in the CRG Loan Agreement, the draw on this facility was not considered for purposes of this exercise; and


•	No public or private equity transactions can be considered for purposes of this exercise in the absence of any existing or committed arrangements to raise additional capital.

In performing the first step of the assessment, we concluded that the following conditions raise substantial doubt about our ability to meet our financial obligations as they become due. As of December 31, 2017, we had $83.7 million in cash, cash equivalents and short-term investments and $17.1 million of accounts receivable. We have a history of net losses ($53.5 million in 2017) and use of cash for operations ($36.2 million in 2017). In addition, on January 1, 2018, transitional pass-through reimbursement for our only commercial product, OMIDRIA, which allowed for separate payment (i.e., outside the packaged procedural payment) under Medicare Part B expired as scheduled and we cannot predict future revenues.

In performing the second step of this assessment, we are required to evaluate whether our plans to mitigate the conditions above alleviate the substantial doubt about our ability to meet our obligations as they become due within one year after the date the financial statements are issued. In performing this second step of the assessment, we are limited to those assumptions listed above and the restrictions and definitions in the Standard. As such, we did not consider any future sources of working capital that we may otherwise be able to access. Consequently, based on this assessment performed using the associated limitations required by the Standard, we have concluded there is substantial doubt about our ability to continue as a going concern through March 1, 2019.

If we are unable to raise additional equity, debt or partnering capital when needed through one or more of the avenues previously listed, or upon acceptable terms, such failure would have a significant negative impact on our financial condition. Should it be necessary to manage our operating expenses, we would reduce our projected cash requirements through reduction of our expenses by delaying clinical trials, reducing selected research and development efforts, or implementing other restructuring activities.

The accompanying consolidated financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The accompanying consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from uncertainty related to our ability to continue as a going concern.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Significant Accounting Policies

Cash and Cash Equivalents, Short-Term Investments and Restricted Cash and Investments

Cash and cash equivalents include highly liquid investments with a maturity of three months or less on the date of purchase. Short-term investment securities are classified as available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are reported as a separate component of shareholders’ deficit. Amortization, accretion, interest and dividends, realized gains and losses and declines in value judged to be other-than-temporary are included in other income. The cost of securities sold is based on the specific-identification method. Investments in securities with maturities of less than one year, or those for which management intends to use the investments to fund current operations, are included in current assets. We evaluate whether an investment is other-than-temporarily impaired based on the specific facts and circumstances. Factors that are considered in determining whether an other-than-temporary decline in value has occurred include: the market value of the security in relation to its cost basis; the financial condition of the investee; and the intent and ability to retain the investment for a sufficient period of time to allow for recovery in the market value of the investment. Restricted cash and investments are held in certificates of deposit and money-market funds.

As of December 31, 2017 and 2016, all investments are classified as short-term and available-for-sale on the accompanying Consolidated Balance Sheets. Investment income, which is included as a component of other income, consists primarily of interest earned.

Inventory

Inventory is stated at the lower of cost or market determined on a specific identification basis in a manner which approximates the first-in, first-out (FIFO) method. Costs include amounts related to third party manufacturing, transportation and internal labor and overhead. Capitalization of costs as inventory begins when the product candidate receives regulatory approval in the U.S. or the European Union (EU). We expense inventory costs related to product candidates as research and development expenses prior to receiving regulatory approval in the respective territory. Inventory is reduced to net realizable value for excess and obsolete inventories based on forecasted demand.

Receivables, Net

Receivables relate primarily to sales of OMIDRIA to wholesalers and include reductions for estimated chargebacks and product returns from wholesalers which are expected to be settled through reductions in receivables. Remaining receivables consist of amounts from subleases for space in The Omeros Building. Considering the nature and historic collectability of our receivables, we concluded an allowance for doubtful accounts is not necessary as of December 31, 2017 and 2016.

Property and Equipment, Net

Property and equipment are stated at cost and depreciation is calculated using the straight-line method over the estimated useful life of the assets, which is generally three to 10 years. Equipment financed under capital leases is recorded as property and equipment and is amortized over the shorter of the useful lives of the related assets or the lease term. Expenditures for repairs and maintenance are expensed as incurred.

Impairment of Long-Lived Assets

The carrying amount of long-lived assets is reviewed whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Recoverability of these assets is measured by comparing the carrying value to future undiscounted cash flows the asset is expected to generate. If the asset is considered to be impaired, the amount of any impairment will be reflected in the results of operations in the period of impairment. We have not recognized any impairment losses for the years ending December 31, 2017, 2016 and 2015.

Deferred Rent

We recognize rent expense on a straight-line basis over the noncancelable term of The Omeros Building operating lease and, accordingly, record the difference between cash rent payments and the recognition of rent expense as an increase or decrease in deferred rent liability. We also record landlord-funded lease incentives, such as reimbursable leasehold improvements, as an increase in deferred rent liability which is amortized as a reduction of rent expense over the noncancelable terms of The Omeros Building operating lease.

Revenue Recognition

Our revenues are primarily comprised of product sales of OMIDRIA. Revenue is recognized when there is persuasive evidence that an arrangement exists, product title and risk of loss is passed to the customer or the service has been provided, the price is fixed or determinable and collection is reasonably assured.

Product Sales, Net

We generally record revenue from product sales when the product is delivered to our wholesalers. Product sales to a wholesaler are not recorded as revenue if we determine that the wholesaler’s on-hand OMIDRIA inventory, based on sell-through and inventory information we regularly receive from our wholesalers, exceeds approximately eight weeks of projected demand.

The Centers for Medicare and Medicaid Services (CMS) granted transitional pass-through reimbursement status for OMIDRIA through January 1, 2018. Pass-through status for OMIDRIA allowed for reimbursement payment to Ambulatory Surgery Centers (ASCs) and hospitals using OMIDRIA in procedures involving patients covered by Medicare Part B. As a result of this expiration, we saw a significant reduction in ASC and hospital demand for OMIDRIA beginning in December 2017 as surgical facilities utilized inventories and this reduction has continued in 2018 due to uncertainty around OMIDRIA reimbursement. Consequently, we did not recognize revenue for wholesaler on-hand OMIDRIA inventory at December 31, 2017 in excess of eight weeks of projected ASC and hospital demand.

Product sales are recorded net of wholesaler distribution fees and estimated chargebacks, product returns, rebates and purchase volume discounts. Accruals or allowances are established for these deductions in the same period when revenue is recognized, and actual amounts incurred are offset against the applicable accruals or allowances. We reflect each of these accruals or allowances as either a reduction in the related account receivable or as an accrued liability, depending on how the amount is expected to be settled.

We also accept returns from our ASCs and hospitals who have purchased OMIDRIA from our wholesalers. Due to the expiration of pass-through, we expect the ASCs and hospitals will return a portion of their OMIDRIA on hand at December 31, 2017 to us for a full refund of the purchase price.

Research and Development

Research and development costs are comprised primarily of costs for personnel, including salaries, benefits and stock compensation; an allocation of our occupancy costs; clinical study costs; contracted research; manufacturing; consulting arrangements; depreciation; materials and supplies; milestones; and other expenses incurred to sustain our overall research and development programs. Research and development costs are expensed as incurred.

Advance payments for goods or services that will be used or rendered for future research and development activities are deferred and then recognized as an expense as the related goods are delivered or the services are performed, or when the goods or services are no longer expected to be provided.

Patents

We generally apply for patent protection on processes and product candidates we or our licensors conceive or develop. Patent costs are comprised primarily of external legal fees, filing fees incurred to file patent applications, and periodic renewal fees to keep the patent in force and are expensed as incurred as a component of general and administrative expense.

Selling, General and Administrative

Selling, general and administrative (SG&A) expenses are comprised primarily of salaries, benefits, and stock-compensation costs for sales, marketing, and other personnel not directly engaged in research and development. Additionally, SG&A includes marketing and selling expenses, professional and legal services; patent costs; depreciation, an allocation of our occupancy costs; and other general corporate expenses. Advertising costs, which we consider to be media and marketing materials, are expensed as incurred and were $328,000, $672,000 and $885,000 during the years ended December 31, 2017, 2016 and 2015, respectively.

Income Taxes

Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their tax bases. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. We recognize the effect of income tax positions only if those positions are more likely than not of being sustained upon an examination. A valuation allowance is established when it is more likely than not that the deferred tax assets will not be realized.

In December 2017, the Tax Cuts and Jobs Act (the Tax Act) was enacted into law and the new legislation contains certain tax provisions that affected us, including a reduction of the federal corporate income tax rate to 21.0% effective January 1, 2018, among others. We are required to recognize the effect of the tax law changes in the period of enactment, such as re-measuring its deferred tax assets and liabilities as well as our valuation allowance against our net deferred tax assets. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), “Income Tax Accounting Implications of the 2017 Tax Cuts and Jobs Act”, which require us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. Since the Tax Act was passed in December 2017, and ongoing guidance and accounting interpretation are expected over the next 12 months, we consider the accounting of the deferred tax re-measurements to be incomplete. We expect to complete our analysis within the one year measurement period.

Stock-Based Compensation

Stock-based compensation expense is recognized for all share-based payments made to employees, directors and non-employees based on estimated fair values. The fair value of our stock options is calculated using the Black-Scholes option-pricing model which requires judgmental assumptions including volatility, forfeiture rates and expected option life. For employees and directors, we use the straight-line method to allocate compensation cost to reporting periods over each optionee’s requisite service period, which is generally the vesting period. Stock options granted to non-employees are accounted for using the fair-value approach and are subject to periodic revaluation over their vesting terms as earned. The stock compensation cost related to non-employee stock options is based on changes in estimated fair value and is charged to expense over the applicable service period.

Accumulated Other Comprehensive Loss

Accumulated other comprehensive loss is comprised of net loss and certain changes in equity that are excluded from net loss. There was no difference between comprehensive loss and net loss for the years ended December 31, 2017, 2016 or 2015.

Financial Instruments and Concentrations of Credit Risk

Cash and cash equivalents, receivables, accounts payable and accrued liabilities, which are recorded at invoiced amount or cost, approximate fair value based on the short-term nature of these financial instruments. The fair value of short-term investments is based on quoted market prices. Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents, short-term investments and receivables. Cash and cash equivalents are held by financial institutions and are federally insured up to certain limits. At times, our cash and cash equivalents balance exceeds the federally insured limits. To limit the credit risk, we invest our excess cash in high quality securities such as money market mutual funds, certificates of deposit and commercial paper.

Our notes payable includes features that meet the requirements under existing accounting guidance to be bifurcated from the respective notes payable agreement and to be recorded at fair value as a derivative asset or liability on the Consolidated Balance Sheet with the corresponding change in fair value recognized in other income on the Consolidated Statement of Operations. As of December 31, 2017 and 2016, the fair value of the embedded derivatives was not material.

Major Customers

We sell OMIDRIA through a limited number of wholesalers. Each of these wholesalers, together with entities under their common control, accounted for greater than 10% of total revenues for the years ended December 31, 2017, 2016 and 2015 and greater than 10% of accounts receivable as of December 31, 2017 and 2016 as noted below.



	2017				2016				2015
	Percentage of Total Revenue		Percentage of Accounts Receivable		Percentage of Total Revenue		Percentage of Accounts Receivable		Percentage of Total Revenue
Distributor A	29	%	31	%	32	%	29	%	31	%
Distributor B	26	%	23	%	31	%	27	%	37	%
Distributor C	22	%	26	%	28	%	24	%	28	%
Distributor D	23	%	20	%	*		19	%	*

* Distributor did not account for greater than 10% of total revenues for the year ended December 31, 2016 or 2015.

Major Suppliers

We use a single contract manufacturer to supply OMIDRIA, and generally one to two contract manufacturers to produce clinical trial material for each of our clinical trials which creates a concentration of risk for us.

We endeavor to maintain reasonable levels of drug supply for our commercial and clinical trial use and other manufacturers are available should we need to change suppliers. A change in suppliers, however, could cause a delay in delivery of OMIDRIA or our clinical trial material that would adversely affect our business.

Recently Adopted Accounting Pronouncements

In 2017, we adopted Accounting Standards Update (ASU) 2016-09 related to stock compensation, which simplifies several aspects of the accounting for share-based payment transactions. Excess tax benefits or deficiencies are now reflected in the Statement of Operations whereas they previously were recognized in equity. We have elected to continue to account for forfeitures based on estimated expected forfeitures.

Recent Accounting Pronouncements

In May 2014, the FASB issued ASU No. 2014-09 (Topic 606) "Revenue from Contracts with Customers." Topic 606 supersedes the revenue recognition requirements in Topic 605 “Revenue Recognition” (Topic 605), and requires entities to recognize revenue when control of the promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. We adopted Topic 606 as of January 1, 2018 using the modified retrospective transition method. Upon adoption, we evaluated our contracts with customers broadly, including our rebate program with qualifying surgery centers, and returns. The adoption of the standard will not change the timing of the recognition of our product sales revenue and will have no material impact on our ongoing results from operations.

In February 2016, the FASB issued ASU 2016-02 related to lease accounting. This standard requires lessees to recognize a right-of-use asset and a lease liability for most leases. This standard must be applied using a modified retrospective transition method and is effective for all annual and interim periods beginning after December 15, 2018. Earlier adoption is permitted. While we are still in the process of evaluating the effect of adoption on our consolidated financial statements and are currently assessing our leases, we expect to adopt the standard January 1, 2019. The adoption will lead to an increase in the assets and liabilities recorded on our Condensed Consolidated Balance Sheets primarily due to the lease agreements for our office building lease. We continue to monitor business activity to ensure we capture all new leasing arrangements upon adoption.

In May 2016, the FASB issued ASU 2017-09 related to stock-based compensation which effectively amends previous issued guidance and provides clarity and consistency in practice on the accounting for changes to the terms and conditions of stock-based payment arrangement, or modifications. This standard is effective for all annual and interim periods beginning after December 15, 2017 and is applied prospectively to modifications occurring after the adoption date. We have adopted the guidance January 1, 2018 and the adoption will not have a material impact on our stock-based compensation expense.

Net Loss Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common share equivalents outstanding for the period, determined using the treasury-stock method. Common share equivalents are excluded from the diluted net loss per share computation if their effect is anti-dilutive.

The basic and diluted net loss per share amounts for the years ended December 31, 2017, 2016 and 2015 were computed based on the shares of common stock outstanding during the respective periods. Potentially dilutive securities excluded from the diluted loss per share calculation are as follows:



	Year Ended December 31,
	2017	2016	2015
Outstanding options to purchase common stock	9,657,259	9,809,374	8,310,235
Warrants and pre-funded warrants to purchase common stock	100,602	100,602	749,250
Total potentially dilutive securities	9,757,861	9,909,976	9,059,485

Accounts Receivable, Net (Notes)

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Accounts Receivable, Net



	December 31,
	2017		2016
	(In thousands)
Trade receivables, net	$	17,079	$	11,937
Sublease and other receivables	65		100
Total accounts receivables net	$	17,144	$	12,037

Trade receivables are shown net of $198,000 and $297,000 of chargeback and product return allowances as of December 31, 2017 and 2016, respectively.

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Fair-Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair-Value Measurements

On a recurring basis, we measure certain financial assets at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, an exit price, in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The accounting standard establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs, where available. The following summarizes the three levels of inputs required:

Level 1—Observable inputs for identical assets or liabilities, such as quoted prices in active markets;

Level 2—Inputs other than quoted prices in active markets that are either directly or indirectly observable; and

Level 3—Unobservable inputs in which little or no market data exists, therefore they are developed using estimates and assumptions developed by us, which reflect those that a market participant would use.

Our fair-value hierarchy for our financial assets measured at fair value on a recurring basis are as follows:



	December 31, 2017
	Level 1		Level 2		Level 3		Total
	(In thousands)
Assets:
Money-market funds classified as non-current restricted cash and investments	$	5,835	$	—	$	—	$	5,835
Money-market funds classified as short-term investments	80,355		—		—		80,355
Total	$	86,190	$	—	$	—	$	86,190



	December 31, 2016
	Level 1		Level 2		Level 3		Total
	(In thousands)
Assets:
Money-market funds classified as non-current restricted cash and investments	$	5,835	$	—	$	—	$	5,835
Money-market funds classified as short-term investments	43,107		—		—		43,107
Total	$	48,942	$	—	$	—	$	48,942

Cash held in demand deposit accounts of $3.4 million and $2.2 million is excluded from our fair-value hierarchy disclosure as of December 31, 2017 and 2016, respectively. There were no unrealized gains or losses associated with our short-term investments as of December 31, 2017 or 2016. The carrying amounts reported in the accompanying Consolidated Balance Sheets for receivables, accounts payable, other current monetary assets and liabilities and notes payable and lease financing obligations approximate fair value.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Certain Balance Sheet Accounts

12 Months Ended

Dec. 31, 2017

Balance Sheet Related Disclosures [Abstract]

Certain Balance Sheet Accounts

Inventory



	December 31,
	2017		2016
	(In thousands)
Raw materials	$	83	$	101
Work-in-process	—		854
Finished goods	360		173
Total inventory cost	$	443	$	1,128

Work-in-process consists of manufactured vials of OMIDRIA that have not been packaged into finished goods.

Property and Equipment, Net



	December 31,
	2017			2016
	(In thousands)
Laboratory equipment	$	2,180		$	1,830
Capital lease equipment	1,915			774
Computer equipment	684			684
Office equipment and furniture	625			625
Total cost	5,404			3,913
Less accumulated depreciation and amortization	(3,283		)	(2,732		)
Total property and equipment, net	$	2,121		$	1,181

For the years ended December 31, 2017, 2016 and 2015, depreciation and amortization expense was $551,000, $300,000 and $209,000, respectively.

Accrued Expenses



	December 31,
	2017		2016
	(In thousands)
Sales rebates, fees and discounts	$	6,561	$	1,773
Contract research and development	4,251		3,030
Employee compensation	2,178		4,551
ASC/hospital product return liability	2,350		—
Consulting and professional fees	1,758		2,223
Clinical trials	1,026		1,167
Other accruals	1,002		610
Total accrued liabilities	$	19,126	$	13,354

Notes Payable and Lease Financing Obligations

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Notes Payable and Lease Financing Obligations

Notes payable and lease financing obligations consist of the following:



	December 31,
	2017			2016
	(In thousands)
Notes payable	$	83,831		$	80,516
Lender facility fee payable upon maturity	4,192			4,025
Lease financing obligations	1,300			522
Notes payable, facility fee and lease financing obligations	89,323			85,063
Unamortized debt discount	(3,527		)	(3,958		)
Unamortized debt issuance costs	(1,189		)	(1,395		)
Current portion of lease financing obligations	(490		)	(198		)
Non-current portion of notes payable and lease financing obligations, net	$	84,117		$	79,512

2015 Oxford/EWB Loan Agreement

In December 2015, we entered into a Loan and Security Agreement (the Oxford/EWB Loan Agreement) with Oxford Finance, LLC (Oxford) and East West Bank (EWB) pursuant to which we borrowed $50.0 million. We used $27.3 million of the loan proceeds to repay all of the amounts owed by us under a previously outstanding loan.

After deducting all loan initiation costs and outstanding interest on the Oxford/MidCap Loan Agreement, we received $22.3 million in net proceeds. We accounted for the termination of the Oxford/Midcap Loan Agreement as a debt extinguishment and, accordingly, incurred a loss of $1.3 million associated with the unamortized loan maturity fee and the prepayment fee.

The Oxford/EWB Loan Agreement required a $3.8 million loan maturity fee upon full repayment of the initial $50.0 million borrowed and $525,000 for each additional $10.0 million borrowed. We had the option to prepay the outstanding principal balance in its entirety at any time if we pay a prepayment equal to 1.0% of the then-outstanding principal balance.

In May 2016, we entered into the First Amendment to the Oxford/EWB Loan Agreement (the Amendment) and borrowed an additional $20.0 million. After deducting all loan initiation costs, we received $19.9 million in net proceeds. In connection with the Amendment, we issued warrants to purchase an aggregate of 100,602 shares of Omeros common stock (the Warrants) to Oxford and EWB at the then current market price of $9.94 per share. We accounted for the Warrants as a discount to our notes payable (see Note 9 for further discussion of the Warrants).

We accounted for the Amendment as a debt modification and, accordingly, the unamortized discount and debt issuance costs associated with the Oxford/EWB Loan Agreement were being amortized to interest expense using the effective interest method over the remaining term of the Oxford/EWB Loan Agreement.

2016 CRG Loan Agreement

In October 2016, we entered into the CRG Loan Agreement with CRG Servicing LLC (CRG), as administrative and collateral agent, and the lenders identified therein and, in November 2016, borrowed $80.0 million. We used $75.7 million of the loan proceeds to repay all amounts owed by us under our then-outstanding Oxford/EWB Loan Agreement. After deducting the loan initiation costs and related fees on the CRG Loan Agreement, we received $3.0 million in net proceeds. We accounted for the termination of the Oxford/EWB Loan Agreement as a debt extinguishment and, accordingly, incurred a loss of $5.6 million associated with the unamortized loan maturity fee, loan initiation costs and the prepayment fee.

In October 2017, we and CRG amended the CRG Loan Agreement so that we will be permitted to borrow, at our sole discretion and subject to customary closing conditions, up to an additional $45.0 million. In February 2018, we and CRG amended the CRG Loan Agreement to extend the borrowing date for the additional $45.0 million through May 20, 2018; none of the other terms or conditions of the CRG Loan Agreement were modified.

The CRG Loan Agreement accrues interest at an annual rate of 12.25% (4.00% of which can be deferred at our option through December 31, 2020 by adding such amount to the aggregate principal amount). Subject to the achievement of certain milestones, this interest-only period could be extended through the maturity date of September 30, 2022. As of December 31, 2017, we have deferred $3.8 million of interest due by increasing the principal amount outstanding. The CRG Loan Agreement requires us to maintain cash and cash equivalents of $5.0 million during the term of the agreement which is recorded as restricted cash and investments in our Consolidated Balance Sheet.

If an OMIDRIA net revenue milestone is satisfied during the 12-month period ending on December 31, 2019, the interest rate may be reduced to 11.50%, 3.50% of which may be deferred at our option and added to the principal amount outstanding. In addition, if either the OMIDRIA net revenue milestone is satisfied during such period or a market capitalization milestone is achieved during the fourth quarter of 2020, the loan would convert to interest-only until the September 30, 2022 maturity.

We are required to pay a facility fee equal to 5.00% of the aggregate principal amount borrowed (including principal additions related to deferred interest) on repayment of the CRG Loan Agreement. The $4.2 million related to the facility fee is being accreted to notes payable using the effective interest method over the term of the CRG Loan Agreement.

We may prepay all or a portion of the outstanding principal under the CRG Loan Agreement at any time subject to a prepayment fee through September 30, 2019, with no prepayment fee thereafter. In certain circumstances, including a change of control and certain asset sales or licensing transactions, we are required to prepay all or a portion of the loan, including the applicable prepayment premium of on the amount of the outstanding principal to be prepaid.

The CRG Loan Agreement also requires us to achieve either (a) certain minimum net revenue amounts from any sources, including product sales, licensing and partnering, through the end of 2021, which are $65.0 million and $75.0 million for the 2018 and 2019 calendar years, respectively, or (b) a minimum market capitalization threshold equal to the product of 6.4 multiplied by the aggregate principal amount of loans outstanding under the CRG Loan Agreement ($512.0 million required market capitalization based on the amount borrowed at December 31, 2017) determined as of the fifth business day following announcement of earnings results for the applicable year. If we are unable to satisfy each of the minimum annual revenue requirement and the market capitalization threshold for any given year, we may avoid a related default by repaying the shortfall between actual revenues and the minimum revenue requirement for such year using proceeds generated by an equity or subordinated debt issuance.

The CRG Loan Agreement includes customary events of default that include, among other things, non-payment, inaccuracy of representations and warranties, covenant breaches, cross default to material indebtedness or material agreements, bankruptcy and insolvency, material judgments and a change of control. An event of default under the CRG Loan Agreement also includes the occurrence of any material adverse effect upon our business, condition (financial or otherwise), operations, performance or property taken as a whole. If there is an event of default under the CRG Loan Agreement, the lenders may have the right to accelerate all of our repayment obligations under the CRG Loan Agreement and to take control of our pledged assets, which include substantially all of our assets including our intellectual property. Under certain circumstances, a default interest rate of an additional 4.00% per annum will apply on all outstanding obligations during the existence of an event of default under the Loan Agreement.

As of December 31, 2017, we were not in default under the CRG Loan Agreement.

Capital Lease Financing Obligations

We have capital leases for certain laboratory and office equipment that have lease terms expiring through December 2021. Equipment costs related to these capital leases of $1.9 million and $774,000 is included in our property and equipment as of December 31, 2017 and December 31, 2016, respectively and the accumulated depreciation on this equipment was $530,000 and $230,000, respectively. The remaining principal payments under these capital leases totaled $1.3 million as of December 31, 2017.

Future Principal Payments

Future principal payments as of December 31, 2017 under the CRG Loan Agreement and our capital equipment financing leases, based on stated contractual maturities, are as follows:



Year Ending December 31,	Notes Payable		Capital Lease Financing Obligations		Total
	(In thousands)
2018	$	—	$	492	$	492
2019	—		391		391
2020	10,479		232		10,711
2021	41,915		99		42,014
2022	31,437		86		31,523
Total future principal payments	$	83,831	$	1,300	$	85,131

The principal payments reflected in the table above exclude the $4.2 million lender’s facility fee due on repayment of the CRG Loan Agreement.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Lease Obligations

We lease office and laboratory spaces in The Omeros Building. The initial term of the real estate lease ends in November 2027 and we have two options to extend the lease term, each by five years. As of December 31, 2017, the remaining aggregate non-cancelable rent under the initial terms of the real estate lease, excluding common area maintenance and related operating expenses, was $49.7 million. The deferred rent balance of $9.1 million relates to rent deferrals and landlord funded lease incentives and is being amortized to research and development and selling, general and administrative expense on a straight-line basis through the initial term of the lease.

Rent expense, including the amortization of lease incentives and rent deferrals, totaled $4.4 million, $4.4 million and $4.5 million for the years ended December 31, 2017, 2016 and 2015, respectively.

We sublease unused space in The Omeros Building to third-party tenants. Rental income received under these subleases was $886,000, $737,000 and $889,000 for the years ended December 31, 2017, 2016 and 2015, respectively. Rental income is recorded as other income in the accompanying Consolidated Statements of Operations and Comprehensive Loss.

We had no material non-cancelable rental payments relating to equipment at December 31, 2017.

Future minimum payments related to our leases at December 31, 2017, are as follows:



Year Ending December 31,	The Omeros Building Lease		Building Sublease Income		Net Operating Lease Payments
	(In thousands)
2018	$	4,564	$	558	$	4,006
2019	4,660		—		4,660
2020	4,769		—		4,769
2021	4,880		—		4,880
2022	4,995		—		4,995
Thereafter	25,840		—		25,840
Total	$	49,708	$	558	$	49,150

Contracts

We have various agreements with third parties that collectively require payment of termination fees totaling $5.5 million as of December 31, 2017 if we cancel the work within specific time frames, either prior to commencing or during performance of the contracted services. This is in addition to fees associated with the CRG Loan Agreement (see Note 7).

Development Milestones and Product Royalties

We have licensed a variety of intellectual property from third parties that we are currently developing or may develop in the future. These licenses may require milestone payments during the clinical development processes as well as low single to low double-digit royalties on the net income or net sales of the product. For the years ended December 31, 2017, 2016 and 2015, we did not owe any development milestones or royalties.

Litigation

In 2015, Par Pharmaceutical, Inc. and its subsidiary, Par Sterile Products, LLC, (collectively, Par) filed an Abbreviated New Drug Application (ANDA) seeking approval from the FDA to market a generic version of OMIDRIA prior to the expiration of our issued patents and we filed a patent infringement lawsuit under the Hatch-Waxman Act against Par.

In July 2017, a bench trial was held on this matter. In October 2017, we entered into a settlement agreement with Par pursuant to which Par acknowledged and confirmed the validity of our issued U.S. OMIDRIA patents and Par and its affiliates are prohibited from launching a generic version of OMIDRIA until the earlier of April 1, 2032 or a date on which we or a third party is able to launch a generic version of OMIDRIA. Under the settlement agreement, Par is granted a non-exclusive, non-sublicensable license to make, sell and distribute a generic version of OMIDRIA between the permitted launch date and the latest expiration of our U.S. patents related to OMIDRIA (i.e., October 23, 2033). During this period, Par is required to pay us a royalty equal to 15% of Par’s net sales of its generic version of OMIDRIA.

In May 2017, we received Notice Letters from Sandoz Inc. (Sandoz) and Lupin Ltd. and Lupin Pharmaceuticals, Inc. (collectively, Lupin), respectively, that Sandoz and Lupin had each filed an ANDA seeking approval from the FDA to market a generic version of OMIDRIA prior to the expiration our patents covering OMIDRIA. In June 2017, we filed patent infringement lawsuits against Sandoz and Lupin. We believe the assertions in the Sandoz and Lupin are substantially similar to those filed by Par and do not have merit. We intend to prosecute vigorously our infringement claims against each of Sandoz and Lupin.

Shareholders' Equity

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Shareholders' Equity

Shareholders’ Equity

Common Stock

As of December 31, 2017, we had reserved shares of common stock for the following purposes:



Options granted and outstanding	9,657,259
Options available for future grant	3,513,540
Common stock warrants	100,602
Total shares reserved	13,271,401

At Market Issuance Sales Agreement - In 2016, under an At Market Issuance Sales Agreement, we sold 64,565 shares of our common stock at an average price of $11.41 and received net proceeds of $724,000.

Securities Offerings - In August 2017, we sold 3.0 million shares of our common stock at a public offering price of $22.75 per share. After deducting underwriter discounts and offering expenses of $4.6 million, we received net proceeds from the transaction of $63.6 million.

In August 2016, we sold 3.5 million shares of our common stock at a public offering price of $11.50 per share. After deducting underwriter discounts and offering expenses, we received net proceeds from the offering of $37.3 million.

In February 2015, we sold 3.4 million shares of our common stock at a public offering price of $20.03 and sold pre-funded warrants to purchase up to 749,250 shares of our common stock at a public offering price of $20.02 per pre-funded warrant share. The public offering price for the pre-funded warrants was equal to the public offering price of the common stock, less the $0.01 per share exercise price of each pre-funded warrant. After deducting underwriter discounts and offering expenses of $4.9 million, we received net proceeds from the transaction of $79.1 million.

Warrants

The following table summarizes our outstanding warrants at December 31, 2017:



Outstanding At December 31, 2017	Expiration Date	Exercise Price
100,602	May 18, 2023	$9.94

In connection with the Amendment to the Oxford/EWB Loan Agreement in May 2016, we issued warrants to purchase an aggregate of 100,602 shares of our common stock. As of December 31, 2017, these warrants remain outstanding and are exercisable through May 18, 2023 at an exercise price per share of $9.94 per share.

In March 2016, we received cash proceeds of approximately $7,500 upon the cash exercise of our then-outstanding pre-funded warrants related to our securities offering in February 2015. The warrants had an exercise price of $0.01 per share, and the exercise resulted in the issuance of 749,250 shares of our common stock.

In March 2009, we issued warrants with an exercise price of $12.25 per share to brokers who assisted us in our Series E financing (the Series E Warrants). For the year ended December 31, 2015, we received cash proceeds of $1.4 million upon the cash and cashless exercise of Series E Warrants which resulted in the issuance of 133,240 shares of our common stock. All of the unexercised warrants expired during the year ended December 31, 2015.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

On June 16, 2017, our shareholders approved the Omeros Corporation 2017 Omnibus Incentive Compensation Plan (the 2017 Plan), which provides for the grant of incentive and non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units, performance units, performance shares and other stock and cash awards to employees, directors and consultants and subsidiary corporations’ employees and consultants. The 2017 Plan replaces the Omeros Corporation 2008 Equity Incentive Plan (the 2008 Plan) and as a result we will not grant any new awards under the 2008 Plan. Any stock option awards granted under the 2008 Plan that were outstanding as of the effective date of the 2017 Plan remain in effect pursuant to their terms and, if the award is canceled or is repurchased, the shares underlying such award become available for grant under the 2017 Plan. Under the 2017 Plan, stock options must be granted with exercise prices not less than the fair market value of the common stock subject to the stock option on the date of the grant and the options may not exceed 10 years.

Under the 2008 Plan, we granted incentive and non-statutory stock options to employees, directors and non-employees. Options were granted with exercise prices equal to the closing fair market value of the common stock on the date of the grant. The options granted were generally for 10-year terms and vested over a four-year period.

As of December 31, 2017, a total of 13,271,887 shares were reserved for issuance under our stock plans, of which 3,513,540 were available for future grants.

Stock-based compensation expense includes amortization of stock options granted to employees, directors and non-employees and has been reported in our Consolidated Statements of Operations and Comprehensive Loss as follows:



	Year Ended December 31,
	2017		2016		2015
	(In thousands)
Research and development	$	5,240	$	6,304	$	4,977
Selling, general and administrative	7,448		7,278		4,604
Total stock-based compensation expense	$	12,688	$	13,582	$	9,581

The fair value of each option grant to employees and directors is estimated on the date of grant using the Black-Scholes option-pricing model. The following assumptions were applied to employee and director stock option grants during the periods ended:



	Year Ended December 31,
	2017			2016			2015
Estimated weighted-average fair value	$	8.66		$	6.89		$	11.31
Weighted-average assumptions:
Expected volatility	74		%	74		%	71		%
Expected term, in years	6.0			5.7			6.0
Risk-free interest rate	2.05		%	1.63		%	1.68		%
Expected dividend yield	—		%	—		%	—		%

During the years ended December 31, 2017, 2016 and 2015, we granted to non-employees options to purchase 25,000 shares, 38,000 shares and 4,200 shares of common stock, respectively.

In connection with the non-employee options, we recognized expense of $549,000, $313,000 and $492,000 during the years ended December 31, 2017, 2016 and 2015, respectively.

Stock option activity for all stock plans is as follows:



	Options Outstanding		Weighted- Average Exercise Price per Share		Remaining Contractual Life (in years)	Aggregate Intrinsic Value (In thousands)
Balance at December 31, 2016	9,809,374		$	9.66
Granted	1,825,140		13.14
Exercised	(1,392,093	)	8.45
Forfeited/expired	(585,162	)	11.13
Balance at December 31, 2017	9,657,259		$	10.39	6.77	$	88,096
Vested and expected to vest at December 31, 2017	9,362,096		$	10.32	6.71	$	85,998
Exercisable at December 31, 2017	6,811,348		$	9.57	5.93	$	67,373

The total intrinsic value of options exercised during the years ended December 31, 2017, 2016 and 2015 was $16.4 million, $13.6 million and $3.9 million, respectively.

At December 31, 2017, there were 2,845,911 unvested options outstanding that will vest over a weighted-average period of 2.4 years. Excluding non-employee stock options, the remaining estimated compensation expense to be recognized in connection with these unvested options is $18.6 million.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

We have a history of losses and therefore have made no provision for income taxes. Deferred income taxes reflect the tax effect of net operating loss and tax credit carryforwards and the net temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.

Significant components of deferred income taxes are as follows:



	December 31,
	2017			2016
	(In thousands)
Deferred tax assets:
Net operating loss carryforwards	$	90,498		$	126,410
Tax credit carryforwards	26,748			18,741
Stock-based compensation	7,829			11,102
Deferred rent	2,123			3,318
Other	4,749			4,401
Total deferred tax assets	131,947			163,972
Less valuation allowance	(131,947		)	(163,972		)
Net deferred tax assets	$	—		$	—

As of December 31, 2017 and 2016, we had federal net operating loss carryforwards of approximately $414.5 million and $378.9 million, respectively, state net operating losses of approximately $68.9 million and $50.0 million, respectively.

As of December 31, 2017, we remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21.0%. However, we are still analyzing certain aspects of the Tax Act, which could potentially affect the measurement of these assets and liabilities or potentially give rise to new deferred tax assets and liabilities. The provisional amount recorded related to the remeasurement of our deferred tax balance was $61.3 million.

In certain circumstances, due to ownership changes, our net operating loss and tax credit carryforwards may be subject to limitations under Section 382 of the Internal Revenue Code. To date, we have not completed a Section 382 study. Unless previously utilized, our net operating loss and research and development tax credit carryforwards expire between 2018 and 2036.

We have established a 100% valuation allowance due to the uncertainty of our ability to generate sufficient taxable income to realize the deferred tax assets. Our valuation allowance decreased $32.0 million, increased $24.9 million and increased $30.4 million in 2017, 2016 and 2015, respectively, primarily due to net operating losses incurred during these periods.

Reconciliation of income tax computed at federal statutory rates to the reported provisions for income taxes is as follows:



	Year ended December 31,
	2017		2016		2015
U.S. Federal statutory rate on net loss	(34	)%	(34	)%	(34	)%
State tax, net of federal tax benefit	(2	)%	(2	)%	(2	)%
Effects of statutory rate change	115	%	—	%	—	%
Change in valuation allowance	(60	)%	37	%	41	%
Tax credits	(11	)%	(4	)%	(5	)%
Other	(8	)%	3	%	—	%
Effective tax rate	—	%	—	%	—	%

We file federal and certain state income tax returns, which provides varying statutes of limitations on assessments. However, because of net operating loss carryforwards, substantially all of our tax years remain open to federal and state tax examination.

We recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense. To date, there have been no interest or penalties charged to us in relation to the underpayment of income taxes.

Quarterly Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Information (Unaudited)

The following table summarizes the unaudited statements of operations and comprehensive loss for each quarter of 2017 and 2016 (in thousands, except per share amounts):



2017	For the Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Revenue	$	12,257		$	17,151		$	21,658		$	13,760
Total costs and expenses	24,982			29,090			26,768			27,881
Loss from operations	(12,725		)	(11,939		)	(5,110		)	(14,121		)
Net loss	(15,089		)	(14,359		)	(7,482		)	(16,551		)
Basic and diluted net loss per share	$	(0.34	)	$	(0.33	)	$	(0.16	)	$	(0.34	)


2016	For the Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Revenue	$	7,419		$	10,004		$	11,289		$	12,905
Total costs and expenses	26,871			20,933			23,327			24,762
Loss from operations	(19,452		)	(10,929		)	(12,038		)	(11,857		)
Net loss	(20,539		)	(12,612		)	(13,962		)	(19,632		)
Basic and diluted net loss per share	$	(0.54	)	$	(0.32	)	$	(0.34	)	$	(0.45	)

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Organization	Organization We are a commercial-stage biopharmaceutical company committed to discovering, developing and commercializing small-molecule and protein therapeutics for large-market as well as orphan indications targeting inflammation, complement-mediated diseases and disorders of the central nervous system. Our first drug product, OMIDRIA, is marketed in the United States (U.S.) for use during cataract surgery or intraocular lens replacement.
Basis of Presentation	Basis of Presentation Our consolidated financial statements include the financial position and results of operations of Omeros Corporation (Omeros) and our wholly owned subsidiaries. All inter-company transactions have been eliminated. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP).
Segments	Segments We operate in one segment. Management uses cash flow as the primary measure to manage our business and does not segment our business for internal reporting or decision-making.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant items subject to such estimates include revenue recognition, stock-based compensation expense and accruals for clinical trials, manufacturing of drug product and clinical drug supply and contingencies. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances; however, actual results could differ from these estimates.
Cash and Cash Equivalents, Short-Term Investments and Restricted Cash and Investments	Cash and Cash Equivalents, Short-Term Investments and Restricted Cash and Investments Cash and cash equivalents include highly liquid investments with a maturity of three months or less on the date of purchase. Short-term investment securities are classified as available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are reported as a separate component of shareholders’ deficit. Amortization, accretion, interest and dividends, realized gains and losses and declines in value judged to be other-than-temporary are included in other income. The cost of securities sold is based on the specific-identification method. Investments in securities with maturities of less than one year, or those for which management intends to use the investments to fund current operations, are included in current assets. We evaluate whether an investment is other-than-temporarily impaired based on the specific facts and circumstances. Factors that are considered in determining whether an other-than-temporary decline in value has occurred include: the market value of the security in relation to its cost basis; the financial condition of the investee; and the intent and ability to retain the investment for a sufficient period of time to allow for recovery in the market value of the investment. Restricted cash and investments are held in certificates of deposit and money-market funds. As of December 31, 2017 and 2016, all investments are classified as short-term and available-for-sale on the accompanying Consolidated Balance Sheets. Investment income, which is included as a component of other income, consists primarily of interest earned.
Inventory	Inventory Inventory is stated at the lower of cost or market determined on a specific identification basis in a manner which approximates the first-in, first-out (FIFO) method. Costs include amounts related to third party manufacturing, transportation and internal labor and overhead. Capitalization of costs as inventory begins when the product candidate receives regulatory approval in the U.S. or the European Union (EU). We expense inventory costs related to product candidates as research and development expenses prior to receiving regulatory approval in the respective territory. Inventory is reduced to net realizable value for excess and obsolete inventories based on forecasted demand.
Receivables, Net	Receivables, Net Receivables relate primarily to sales of OMIDRIA to wholesalers and include reductions for estimated chargebacks and product returns from wholesalers which are expected to be settled through reductions in receivables. Remaining receivables consist of amounts from subleases for space in The Omeros Building. Considering the nature and historic collectability of our receivables, we concluded an allowance for doubtful accounts is not necessary as of December 31, 2017 and 2016.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost and depreciation is calculated using the straight-line method over the estimated useful life of the assets, which is generally three to 10 years. Equipment financed under capital leases is recorded as property and equipment and is amortized over the shorter of the useful lives of the related assets or the lease term. Expenditures for repairs and maintenance are expensed as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The carrying amount of long-lived assets is reviewed whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Recoverability of these assets is measured by comparing the carrying value to future undiscounted cash flows the asset is expected to generate. If the asset is considered to be impaired, the amount of any impairment will be reflected in the results of operations in the period of impairment. We have not recognized any impairment losses for the years ending December 31, 2017, 2016 and 2015.
Deferred Rent	Deferred Rent We recognize rent expense on a straight-line basis over the noncancelable term of The Omeros Building operating lease and, accordingly, record the difference between cash rent payments and the recognition of rent expense as an increase or decrease in deferred rent liability. We also record landlord-funded lease incentives, such as reimbursable leasehold improvements, as an increase in deferred rent liability which is amortized as a reduction of rent expense over the noncancelable terms of The Omeros Building operating lease.
Revenue Recognition	Revenue Recognition Our revenues are primarily comprised of product sales of OMIDRIA. Revenue is recognized when there is persuasive evidence that an arrangement exists, product title and risk of loss is passed to the customer or the service has been provided, the price is fixed or determinable and collection is reasonably assured. Product Sales, Net We generally record revenue from product sales when the product is delivered to our wholesalers. Product sales to a wholesaler are not recorded as revenue if we determine that the wholesaler’s on-hand OMIDRIA inventory, based on sell-through and inventory information we regularly receive from our wholesalers, exceeds approximately eight weeks of projected demand. The Centers for Medicare and Medicaid Services (CMS) granted transitional pass-through reimbursement status for OMIDRIA through January 1, 2018. Pass-through status for OMIDRIA allowed for reimbursement payment to Ambulatory Surgery Centers (ASCs) and hospitals using OMIDRIA in procedures involving patients covered by Medicare Part B. As a result of this expiration, we saw a significant reduction in ASC and hospital demand for OMIDRIA beginning in December 2017 as surgical facilities utilized inventories and this reduction has continued in 2018 due to uncertainty around OMIDRIA reimbursement. Consequently, we did not recognize revenue for wholesaler on-hand OMIDRIA inventory at December 31, 2017 in excess of eight weeks of projected ASC and hospital demand. Product sales are recorded net of wholesaler distribution fees and estimated chargebacks, product returns, rebates and purchase volume discounts. Accruals or allowances are established for these deductions in the same period when revenue is recognized, and actual amounts incurred are offset against the applicable accruals or allowances. We reflect each of these accruals or allowances as either a reduction in the related account receivable or as an accrued liability, depending on how the amount is expected to be settled. We also accept returns from our ASCs and hospitals who have purchased OMIDRIA from our wholesalers. Due to the expiration of pass-through, we expect the ASCs and hospitals will return a portion of their OMIDRIA on hand at December 31, 2017 to us for a full refund of the purchase price.
Research and Development	Research and Development Research and development costs are comprised primarily of costs for personnel, including salaries, benefits and stock compensation; an allocation of our occupancy costs; clinical study costs; contracted research; manufacturing; consulting arrangements; depreciation; materials and supplies; milestones; and other expenses incurred to sustain our overall research and development programs. Research and development costs are expensed as incurred. Advance payments for goods or services that will be used or rendered for future research and development activities are deferred and then recognized as an expense as the related goods are delivered or the services are performed, or when the goods or services are no longer expected to be provided.
Patents	Patents We generally apply for patent protection on processes and product candidates we or our licensors conceive or develop. Patent costs are comprised primarily of external legal fees, filing fees incurred to file patent applications, and periodic renewal fees to keep the patent in force and are expensed as incurred as a component of general and administrative expense.
Selling, General and Administrative	Selling, General and Administrative Selling, general and administrative (SG&A) expenses are comprised primarily of salaries, benefits, and stock-compensation costs for sales, marketing, and other personnel not directly engaged in research and development. Additionally, SG&A includes marketing and selling expenses, professional and legal services; patent costs; depreciation, an allocation of our occupancy costs; and other general corporate expenses.
Advertising	Advertising costs, which we consider to be media and marketing materials, are expensed as incurred and were $328,000, $672,000 and $885,000 during the years ended December 31, 2017, 2016 and 2015, respectively.
Income Taxes	Income Taxes Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their tax bases. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. We recognize the effect of income tax positions only if those positions are more likely than not of being sustained upon an examination. A valuation allowance is established when it is more likely than not that the deferred tax assets will not be realized. In December 2017, the Tax Cuts and Jobs Act (the Tax Act) was enacted into law and the new legislation contains certain tax provisions that affected us, including a reduction of the federal corporate income tax rate to 21.0% effective January 1, 2018, among others. We are required to recognize the effect of the tax law changes in the period of enactment, such as re-measuring its deferred tax assets and liabilities as well as our valuation allowance against our net deferred tax assets. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), “Income Tax Accounting Implications of the 2017 Tax Cuts and Jobs Act”, which require us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. Since the Tax Act was passed in December 2017, and ongoing guidance and accounting interpretation are expected over the next 12 months, we consider the accounting of the deferred tax re-measurements to be incomplete. We expect to complete our analysis within the one year measurement period.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense is recognized for all share-based payments made to employees, directors and non-employees based on estimated fair values. The fair value of our stock options is calculated using the Black-Scholes option-pricing model which requires judgmental assumptions including volatility, forfeiture rates and expected option life. For employees and directors, we use the straight-line method to allocate compensation cost to reporting periods over each optionee’s requisite service period, which is generally the vesting period. Stock options granted to non-employees are accounted for using the fair-value approach and are subject to periodic revaluation over their vesting terms as earned. The stock compensation cost related to non-employee stock options is based on changes in estimated fair value and is charged to expense over the applicable service period.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Accumulated other comprehensive loss is comprised of net loss and certain changes in equity that are excluded from net loss. There was no difference between comprehensive loss and net loss for the years ended December 31, 2017, 2016 or 2015.
Financial Instruments and Concentrations of Credit Risk	Financial Instruments and Concentrations of Credit Risk Cash and cash equivalents, receivables, accounts payable and accrued liabilities, which are recorded at invoiced amount or cost, approximate fair value based on the short-term nature of these financial instruments. The fair value of short-term investments is based on quoted market prices. Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents, short-term investments and receivables. Cash and cash equivalents are held by financial institutions and are federally insured up to certain limits. At times, our cash and cash equivalents balance exceeds the federally insured limits. To limit the credit risk, we invest our excess cash in high quality securities such as money market mutual funds, certificates of deposit and commercial paper. Our notes payable includes features that meet the requirements under existing accounting guidance to be bifurcated from the respective notes payable agreement and to be recorded at fair value as a derivative asset or liability on the Consolidated Balance Sheet with the corresponding change in fair value recognized in other income on the Consolidated Statement of Operations.
Major Customers	Major Customers We sell OMIDRIA through a limited number of wholesalers.
Major Suppliers	Major Suppliers We use a single contract manufacturer to supply OMIDRIA, and generally one to two contract manufacturers to produce clinical trial material for each of our clinical trials which creates a concentration of risk for us. We endeavor to maintain reasonable levels of drug supply for our commercial and clinical trial use and other manufacturers are available should we need to change suppliers. A change in suppliers, however, could cause a delay in delivery of OMIDRIA or our clinical trial material that would adversely affect our business.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In 2017, we adopted Accounting Standards Update (ASU) 2016-09 related to stock compensation, which simplifies several aspects of the accounting for share-based payment transactions. Excess tax benefits or deficiencies are now reflected in the Statement of Operations whereas they previously were recognized in equity. We have elected to continue to account for forfeitures based on estimated expected forfeitures. Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09 (Topic 606) "Revenue from Contracts with Customers." Topic 606 supersedes the revenue recognition requirements in Topic 605 “Revenue Recognition” (Topic 605), and requires entities to recognize revenue when control of the promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. We adopted Topic 606 as of January 1, 2018 using the modified retrospective transition method. Upon adoption, we evaluated our contracts with customers broadly, including our rebate program with qualifying surgery centers, and returns. The adoption of the standard will not change the timing of the recognition of our product sales revenue and will have no material impact on our ongoing results from operations. In February 2016, the FASB issued ASU 2016-02 related to lease accounting. This standard requires lessees to recognize a right-of-use asset and a lease liability for most leases. This standard must be applied using a modified retrospective transition method and is effective for all annual and interim periods beginning after December 15, 2018. Earlier adoption is permitted. While we are still in the process of evaluating the effect of adoption on our consolidated financial statements and are currently assessing our leases, we expect to adopt the standard January 1, 2019. The adoption will lead to an increase in the assets and liabilities recorded on our Condensed Consolidated Balance Sheets primarily due to the lease agreements for our office building lease. We continue to monitor business activity to ensure we capture all new leasing arrangements upon adoption. In May 2016, the FASB issued ASU 2017-09 related to stock-based compensation which effectively amends previous issued guidance and provides clarity and consistency in practice on the accounting for changes to the terms and conditions of stock-based payment arrangement, or modifications. This standard is effective for all annual and interim periods beginning after December 15, 2017 and is applied prospectively to modifications occurring after the adoption date. We have adopted the guidance January 1, 2018 and the adoption will not have a material impact on our stock-based compensation expense.

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Revenue by Major Customers by Reporting Segments



	2017				2016				2015
	Percentage of Total Revenue		Percentage of Accounts Receivable		Percentage of Total Revenue		Percentage of Accounts Receivable		Percentage of Total Revenue
Distributor A	29	%	31	%	32	%	29	%	31	%
Distributor B	26	%	23	%	31	%	27	%	37	%
Distributor C	22	%	26	%	28	%	24	%	28	%
Distributor D	23	%	20	%	*		19	%	*

* Distributor did not account for greater than 10% of total revenues for the year ended December 31, 2016 or 2015.

Fair-Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

Our fair-value hierarchy for our financial assets measured at fair value on a recurring basis are as follows:



	December 31, 2017
	Level 1		Level 2		Level 3		Total
	(In thousands)
Assets:
Money-market funds classified as non-current restricted cash and investments	$	5,835	$	—	$	—	$	5,835
Money-market funds classified as short-term investments	80,355		—		—		80,355
Total	$	86,190	$	—	$	—	$	86,190



	December 31, 2016
	Level 1		Level 2		Level 3		Total
	(In thousands)
Assets:
Money-market funds classified as non-current restricted cash and investments	$	5,835	$	—	$	—	$	5,835
Money-market funds classified as short-term investments	43,107		—		—		43,107
Total	$	48,942	$	—	$	—	$	48,942

Certain Balance Sheet Accounts (Tables)

12 Months Ended

Dec. 31, 2017

Balance Sheet Related Disclosures [Abstract]

Inventory



	December 31,
	2017		2016
	(In thousands)
Raw materials	$	83	$	101
Work-in-process	—		854
Finished goods	360		173
Total inventory cost	$	443	$	1,128

Property and Equipment

Property and Equipment, Net



	December 31,
	2017			2016
	(In thousands)
Laboratory equipment	$	2,180		$	1,830
Capital lease equipment	1,915			774
Computer equipment	684			684
Office equipment and furniture	625			625
Total cost	5,404			3,913
Less accumulated depreciation and amortization	(3,283		)	(2,732		)
Total property and equipment, net	$	2,121		$	1,181

Accrued Expenses



	December 31,
	2017		2016
	(In thousands)
Sales rebates, fees and discounts	$	6,561	$	1,773
Contract research and development	4,251		3,030
Employee compensation	2,178		4,551
ASC/hospital product return liability	2,350		—
Consulting and professional fees	1,758		2,223
Clinical trials	1,026		1,167
Other accruals	1,002		610
Total accrued liabilities	$	19,126	$	13,354

Notes Payable and Lease Financing Obligations (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of notes payable and lease financing obligations

Notes payable and lease financing obligations consist of the following:



	December 31,
	2017			2016
	(In thousands)
Notes payable	$	83,831		$	80,516
Lender facility fee payable upon maturity	4,192			4,025
Lease financing obligations	1,300			522
Notes payable, facility fee and lease financing obligations	89,323			85,063
Unamortized debt discount	(3,527		)	(3,958		)
Unamortized debt issuance costs	(1,189		)	(1,395		)
Current portion of lease financing obligations	(490		)	(198		)
Non-current portion of notes payable and lease financing obligations, net	$	84,117		$	79,512

Contractual Obligation, Fiscal Year Maturity Schedule

Future principal payments as of December 31, 2017 under the CRG Loan Agreement and our capital equipment financing leases, based on stated contractual maturities, are as follows:



Year Ending December 31,	Notes Payable		Capital Lease Financing Obligations		Total
	(In thousands)
2018	$	—	$	492	$	492
2019	—		391		391
2020	10,479		232		10,711
2021	41,915		99		42,014
2022	31,437		86		31,523
Total future principal payments	$	83,831	$	1,300	$	85,131

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Reserved Shares of Common Stock

As of December 31, 2017, we had reserved shares of common stock for the following purposes:



Options granted and outstanding	9,657,259
Options available for future grant	3,513,540
Common stock warrants	100,602
Total shares reserved	13,271,401

Schedule of Stockholders' Equity Note, Warrants or Rights

The following table summarizes our outstanding warrants at December 31, 2017:



Outstanding At December 31, 2017	Expiration Date	Exercise Price
100,602	May 18, 2023	$9.94

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense



	Year Ended December 31,
	2017		2016		2015
	(In thousands)
Research and development	$	5,240	$	6,304	$	4,977
Selling, general and administrative	7,448		7,278		4,604
Total stock-based compensation expense	$	12,688	$	13,582	$	9,581

Schedule of Weighted Average Assumptions For Employee Stock Option Grants



	Year Ended December 31,
	2017			2016			2015
Estimated weighted-average fair value	$	8.66		$	6.89		$	11.31
Weighted-average assumptions:
Expected volatility	74		%	74		%	71		%
Expected term, in years	6.0			5.7			6.0
Risk-free interest rate	2.05		%	1.63		%	1.68		%
Expected dividend yield	—		%	—		%	—		%

Stock Option Activity and Related Information

Stock option activity for all stock plans is as follows:



	Options Outstanding		Weighted- Average Exercise Price per Share		Remaining Contractual Life (in years)	Aggregate Intrinsic Value (In thousands)
Balance at December 31, 2016	9,809,374		$	9.66
Granted	1,825,140		13.14
Exercised	(1,392,093	)	8.45
Forfeited/expired	(585,162	)	11.13
Balance at December 31, 2017	9,657,259		$	10.39	6.77	$	88,096
Vested and expected to vest at December 31, 2017	9,362,096		$	10.32	6.71	$	85,998
Exercisable at December 31, 2017	6,811,348		$	9.57	5.93	$	67,373

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Significant Components of Deferred Tax Assets

Significant components of deferred income taxes are as follows:



	December 31,
	2017			2016
	(In thousands)
Deferred tax assets:
Net operating loss carryforwards	$	90,498		$	126,410
Tax credit carryforwards	26,748			18,741
Stock-based compensation	7,829			11,102
Deferred rent	2,123			3,318
Other	4,749			4,401
Total deferred tax assets	131,947			163,972
Less valuation allowance	(131,947		)	(163,972		)
Net deferred tax assets	$	—		$	—

Reconciliation of Federal Statutory Tax Rate to Effective Income Tax

Reconciliation of income tax computed at federal statutory rates to the reported provisions for income taxes is as follows:



	Year ended December 31,
	2017		2016		2015
U.S. Federal statutory rate on net loss	(34	)%	(34	)%	(34	)%
State tax, net of federal tax benefit	(2	)%	(2	)%	(2	)%
Effects of statutory rate change	115	%	—	%	—	%
Change in valuation allowance	(60	)%	37	%	41	%
Tax credits	(11	)%	(4	)%	(5	)%
Other	(8	)%	3	%	—	%
Effective tax rate	—	%	—	%	—	%

Quarterly Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Summary of Unaudited Statements of Operations

The following table summarizes the unaudited statements of operations and comprehensive loss for each quarter of 2017 and 2016 (in thousands, except per share amounts):



2017	For the Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Revenue	$	12,257		$	17,151		$	21,658		$	13,760
Total costs and expenses	24,982			29,090			26,768			27,881
Loss from operations	(12,725		)	(11,939		)	(5,110		)	(14,121		)
Net loss	(15,089		)	(14,359		)	(7,482		)	(16,551		)
Basic and diluted net loss per share	$	(0.34	)	$	(0.33	)	$	(0.16	)	$	(0.34	)


2016	For the Quarter Ended
	March 31,			June 30,			September 30,			December 31,
Revenue	$	7,419		$	10,004		$	11,289		$	12,905
Total costs and expenses	26,871			20,933			23,327			24,762
Loss from operations	(19,452		)	(10,929		)	(12,038		)	(11,857		)
Net loss	(20,539		)	(12,612		)	(13,962		)	(19,632		)
Basic and diluted net loss per share	$	(0.54	)	$	(0.32	)	$	(0.34	)	$	(0.45	)

Organization and Basis of Presentation - Additional Information (Detail)	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Feb. 26, 2018 USD ($)
Accounting Policies [Abstract]
Number of operating segments \| segment									1
Cash, cash equivalents and marketable securities	$ 83,700,000								$ 83,700,000
Receivables, net	17,144,000				$ 12,037,000				17,144,000	$ 12,037,000
Net loss	$ 16,551,000	$ 7,482,000	$ 14,359,000	$ 15,089,000	$ 19,632,000	$ 13,962,000	$ 12,612,000	$ 20,539,000	53,481,000	66,745,000	$ 75,096,000
Net cash used in operating activities									$ 36,227,000	$ 51,504,000	$ 65,209,000
Subsequent Event \| CRG Loan
Debt Instrument [Line Items]
Line of credit facility, additional advances limit												$ 45,000,000.0

Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Advertising expense	$ 328	$ 672	$ 885
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years

Significant Accounting Policies - Major Customers and Major Suppliers (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Distributor A \| Percentage of Total Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	29.00%	32.00%	31.00%
Distributor A \| Percentage of Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	31.00%	29.00%
Distributor B \| Percentage of Total Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	26.00%	31.00%	37.00%
Distributor B \| Percentage of Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	23.00%	27.00%
Distributor C \| Percentage of Total Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	22.00%	28.00%	28.00%
Distributor C \| Percentage of Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	26.00%	24.00%
Distributor D \| Percentage of Total Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	23.00%
Distributor D \| Percentage of Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	20.00%	19.00%

Net Loss Per Share - Calculation of Historical Outstanding Dilutive Securities Not Included in Diluted Loss Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding dilutive securities not included in diluted loss per share calculation	9,757,861	9,909,976	9,059,485
Outstanding options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding dilutive securities not included in diluted loss per share calculation	9,657,259	9,809,374	8,310,235
Warrants and pre-funded warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding dilutive securities not included in diluted loss per share calculation	100,602	100,602	749,250

Accounts Receivable, Net - Grant and Other Receivables (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Trade receivables, net	$ 17,079,000	$ 11,937,000
Sublease and other receivables	65,000	100,000
Total accounts receivables net	17,144,000	$ 12,037,000
Chargeback	$ 198,000		$ 297,000

Fair-Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total	$ 86,190	$ 48,942
Non Current
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as non-current restricted cash and investments	5,835	5,835
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as short-term investments	80,355	43,107
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total	86,190	48,942
Fair Value, Inputs, Level 1 \| Non Current
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as non-current restricted cash and investments	5,835	5,835
Fair Value, Inputs, Level 1 \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as short-term investments	80,355	43,107
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total	0	0
Fair Value, Inputs, Level 2 \| Non Current
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as non-current restricted cash and investments	0	0
Fair Value, Inputs, Level 2 \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as short-term investments	0	0
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total	0	0
Fair Value, Inputs, Level 3 \| Non Current
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as non-current restricted cash and investments	0	0
Fair Value, Inputs, Level 3 \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money-market funds classified as short-term investments	$ 0	$ 0

Fair-Value Measurements - Narrative (Detail) - USD ($)	12 Months Ended
Fair-Value Measurements - Narrative (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Cash	$ 3,400,000	$ 2,200,000
Unrealized gain (loss) on investments	$ 0	$ 0

Certain Balance Sheet Accounts - Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 83	$ 101
Work-in-process	0	854
Finished goods	360	173
Total inventory cost	$ 443	$ 1,128

Certain Balance Sheet Accounts - Property and Equipment (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 5,404,000	$ 3,913,000
Less accumulated depreciation and amortization	(3,283,000)	(2,732,000)
Total property and equipment, net	2,121,000	1,181,000
Depreciation and amortization	551,000	300,000	$ 209,000
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,180,000	1,830,000
Capital lease equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,915,000	774,000
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	684,000	684,000
Office equipment and furniture
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 625,000	$ 625,000

Certain Balance Sheet Accounts - Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Sales rebates, fees and discounts	$ 6,561	$ 1,773
Contract research and development	4,251	3,030
Employee compensation	2,178	4,551
ASC/hospital product return liability	2,350	0
Consulting and professional fees	1,758	2,223
Clinical trials	1,026	1,167
Other accruals	1,002	610
Total accrued liabilities	$ 19,126	$ 13,354

Notes Payable and Lease Financing Obligations - Schedule of Notes Payable and Lease Financing Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Notes payable	$ 83,831	$ 80,516
Lender facility fee payable upon maturity	4,192	4,025
Lease financing obligations	1,300	522
Notes payable, facility fee and lease financing obligations	89,323	85,063
Unamortized debt discount	(3,527)	(3,958)
Unamortized debt issuance costs	(1,189)	(1,395)
Current portion of lease financing obligations	(490)	(198)
Non-current portion of notes payable and lease financing obligations, net	$ 84,117	$ 79,512

Notes Payable and Lease Financing Obligations - Additional Information (Detail)		1 Months Ended		12 Months Ended
	Oct. 26, 2016 USD ($)	May 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)	Mar. 31, 2016 $ / shares	Feb. 28, 2015 shares	Mar. 31, 2009 $ / shares
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt				$ 0	$ (5,595,000)	$ (1,315,000)
Proceeds from debt issuance				$ 0	100,000,000	$ 50,000,000
Shares of common stock to purchase by warrant (in shares) \| shares				100,602							749,250
Exercise price of warrants (in USD per share) \| $ / shares				$ 9.94						$ 0.01		$ 12.25
Outstanding balance				$ 83,831,000
Lender facility fee payable upon maturity				4,192,000	4,025,000
Capital Leased Assets, Gross					774,000
Capital lease, accumulated depreciation				530,000	$ 230,000
Capital lease, future minimum payments due				1,300,000
Oxford Midcap Loan
Debt Instrument [Line Items]
Debt extinguished			$ 27,300,000
Oxford EWB Loan
Debt Instrument [Line Items]
Loan and security agreement, existing outstanding indebtedness				50,000,000
Repayments of debt	$ 75,700,000
Proceeds from long-term debt			22,300,000
Final payment fee, amount				$ 3,800,000
Prepayment fee as percentage of outstanding principal amount				1.00%
Line of credit facility, additional advances limit				$ 20,000,000
Gain (loss) on early extinguishment of debt			$ (1,300,000)
Fee for each additional $10 million advance				525,000
Line of credit facility, additional advances, increase per tranche				10,000,000
Proceeds from debt issuance		$ 19,900,000
CRG Loan
Debt Instrument [Line Items]
Accrued interest rate	12.25%
Maturity fee, as a percent	5.00%
Debt issued	$ 80,000,000
Net proceeds from issuance of debt	3,000,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 5,600,000
Line of Credit Facility, Additional Borrowing Capacity									$ 45,000,000
Deferred interest rate percentage	4.00%
Debt instrument, covenant compliance, minimum restricted cash and cash equivalents	$ 5,000,000
Debt instrument, potential future interest rate if revenue milestone is satisfied	11.50%
Debt instrument, potential future deferred interest rate if revenue milestone is satisfied	3.50%
Debt instrument, covenant compliance, minimum market capitalization threshold multiplier	6.4
Market capitalization				512,000,000
Increase in interest rate if an event of default occurs	4.00%
Increase in principal amount of debt outstanding from deferred interest				$ 3,800,000
CRG Loan \| Scenario, Forecast
Debt Instrument [Line Items]
Debt instrument, covenant compliance, minimum net revenue amount							$ 75,000,000	$ 65,000,000
Maximum
Debt Instrument [Line Items]
Capital lease expiration date				Dec. 01, 2021

Notes Payable and Lease Financing Obligations - Future Minimum Payment Related Lease (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Notes Payable
2017	$ 0
2018	0
2019	10,479
2020	41,915
2021	31,437
Total future principal payments	83,831
Capital Lease Financing Obligations
2017	492
2018	391
2019	232
2020	99
2021	86
Total future principal payments	1,300
Total
2017	492
2018	391
2019	10,711
2020	42,014
2021	31,523
Total future principal payments	$ 85,131

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Oct. 31, 2017	Dec. 31, 2017 USD ($) lease_extension	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Remaining aggregate non-cancelable rent due		$ 49,708,000
Liabilities subject to compromise, early contract termination fee		5,500,000
Research and development		55,599,000	$ 50,699,000	$ 48,379,000
Royalty percent	15.00%
Helion Biotech ApS
Commitments and Contingencies Disclosure [Line Items]
Research and development		$ 0	0
Building
Commitments and Contingencies Disclosure [Line Items]
Number of Options to extend the lease term \| lease_extension		2
Options to extend the lease term, number of options		5 years
Remaining aggregate non-cancelable rent due		$ 49,700,000
Deferred rent		9,100,000
Rent expense		4,400,000	4,400,000	4,500,000
Sublease revenue		$ 886,000	$ 737,000	$ 889,000

Commitments and Contingencies - Future Minimum Payment Related Lease (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
The Omeros Building Lease
2018	$ 4,564
2019	4,660
2020	4,769
2021	4,880
2022	4,995
Thereafter	25,840
Total	49,708
Building Sublease Income
2018	558
2019	0
2020	0
2021	0
2022	0
Thereafter	0
Total	558
Net Operating Lease Payments
2018	4,006
2019	4,660
2020	4,769
2021	4,880
2022	4,995
Thereafter	25,840
Total	$ 49,150

Shareholders' Equity - Reserved Share of Common Stock (Detail)	Dec. 31, 2017 shares
Reserved Common Stock [Line Items]
Total shares reserved	13,271,401
Options granted and outstanding
Reserved Common Stock [Line Items]
Total shares reserved	9,657,259
Options available for future grant
Reserved Common Stock [Line Items]
Total shares reserved	3,513,540
Common stock warrants
Reserved Common Stock [Line Items]
Total shares reserved	100,602

Shareholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended					12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 21, 2016	Mar. 31, 2016	Feb. 28, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2009
Class of Stock [Line Items]
Issuance of stock (in shares)	3,000,000		3,500,000		3,400,000
Share price (in USD per share)	$ 22.75	$ 11.50			$ 20.03
Payments for Underwriting Expense	$ 4,600,000
Proceeds from issuance of common stock and pre-funded warrants, net	$ 63,600,000	$ 37,300,000			$ 79,100,000	$ 63,657,000	$ 38,039,000	$ 79,076,000
Shares of common stock to purchase by warrant (in shares)					749,250	100,602
Exercise price of warrants (in USD per share)				$ 0.01		$ 9.94			$ 12.25
Payment of stock issuance costs					$ 4,900,000
Warrant expiration date						May 18, 2023
Proceeds from warrant exercises				$ 7,500			$ 1,400,000
Pre-funded warrants
Class of Stock [Line Items]
Share price (in USD per share)					$ 20.02
Exercise price of warrants (in USD per share)					$ 0.01
At The Market (ATM) Program
Class of Stock [Line Items]
Issuance of stock (in shares)							64,565
Proceeds from issuance of common stock and pre-funded warrants, net							$ 724,000
At The Market (ATM) Program \| Weighted Average
Class of Stock [Line Items]
Share price (in USD per share)							$ 11.41
Common Stock
Class of Stock [Line Items]
Issuance of stock (in shares)						3,000,000	3,478,260	3,444,831
Issuance of common stock utilizing At-The-Market Agreement (in shares)							749,250	133,240

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, maximum term	6 years 3 days	5 years 8 months 12 days	5 years 11 months 15 days
Shares granted in period	1,825,140
Non-employee options granted (in shares)	25,000	38,000	4,200
Issuance of warrants in connection with amendment to notes payable	$ 549	$ 313	$ 492,000
Total intrinsic value of options exercised	$ 16,400	$ 13,600	$ 3,900
Unvested options outstanding (in shares)	2,845,911
Unvested options outstanding, vesting period	2 years 5 months 8 days
Unrecognized compensation expense	$ 18,600
Equity Incentive Plan 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, average vesting period	4 years
Shares reserved for issuance	13,271,887
Shares available for grant	3,513,540
Equity Incentive Plan 2008 \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, maximum term	10 years

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 12,688	$ 13,582	$ 9,581
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	5,240	6,304	4,977
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 7,448	$ 7,278	$ 4,604

Stock-Based Compensation - Fair Value of Employee Option Grant Estimated on Date of Grant (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted-Average Assumptions
Estimated weighted-average fair value (in dollars per share)	$ 8.66	$ 6.89	$ 11.31
Expected volatility	74.00%	74.00%	71.00%
Expected term, in years	6 years 3 days	5 years 8 months 12 days	5 years 11 months 15 days
Risk-free interest rate	2.05%	1.63%	1.68%
Expected dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Summary of Stock Option Activity and Related Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Options Outstanding
Beginning balance (in shares) \| shares	9,809,374
Granted (in shares) \| shares	1,825,140
Exercised (in shares) \| shares	(1,392,093)
Forfeited and expired (in shares) \| shares	(585,162)
Ending balance (in shares) \| shares	9,657,259
Vested and expected to vest (in shares) \| shares	9,362,096
Exercisable at December 31, 2016 (in shares) \| shares	6,811,348
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share) \| $ / shares	$ 9.66
Granted (in dollars per share) \| $ / shares	13.14
Exercised (in dollars per share) \| $ / shares	8.45
Forfeited and expired (in dollars per share) \| $ / shares	11.13
Ending balance (in dollars per share) \| $ / shares	10.39
Vested and expected to vest (in dollars per share) \| $ / shares	10.32
Exercisable at December 31, 2016 (in dollars per share) \| $ / shares	$ 9.57
Weighted- Average Remaining Contractual Life
Balance at December 31, 2017	6 years 9 months 7 days
Vested and expected to vest at December 31, 2017	6 years 8 months 15 days
Exercisable at December 31, 2017	5 years 11 months 4 days
Aggregate Intrinsic Value
Balance at December 31, 2017 \| $	$ 88,096
Vested and expected to vest at December 31, 2017 \| $	85,998
Exercisable at December 31, 2017 \| $	$ 67,373

Income Taxes - Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 90,498	$ 126,410
Tax credit carryforwards	26,748	18,741
Stock-based compensation	7,829	11,102
Deferred rent	2,123	3,318
Other	4,749	4,401
Total deferred tax assets	131,947	163,972
Less valuation allowance	(131,947)	(163,972)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Operating loss carryforwards	$ 414,500	$ 378,900
Operating loss carryforward, state	68,900	50,000
Remeasurement of our deferred tax	61,300
Research and development tax credit	$ 26,748	18,741
Beginning year of net operating loss expiration	2018
Ending year of net operating loss expiration	2036
Deferred tax assets, percentage of valuation allowance	100.00%
Increase (decrease) in deferred tax valuation allowance	$ (32,000)	$ 24,900	$ 30,400

Income Taxes - Reconciliation of Federal Statutory Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. Federal statutory rate on net loss	(34.00%)	(34.00%)	(34.00%)
State tax, net of federal tax effect	(2.00%)	(2.00%)	(2.00%)
Effects of statutory rate change	115.00%	0.00%	0.00%
Change in valuation allowance	(60.00%)	37.00%	41.00%
Tax credits	(11.00%)	(4.00%)	(5.00%)
Other	(8.00%)	2.60%	(0.00%)
Other	0.00%	0.00%	0.00%

Quarterly Information (Unaudited) - Quarterly Unaudited Statements of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 13,760	$ 21,658	$ 17,151	$ 12,257	$ 12,905	$ 11,289	$ 10,004	$ 7,419	$ 64,826	$ 41,617	$ 13,509
Total costs and expenses	27,881	26,768	29,090	24,982	24,762	23,327	20,933	26,871	108,721	95,893	84,747
Loss from operations	(14,121)	(5,110)	(11,939)	(12,725)	(11,857)	(12,038)	(10,929)	(19,452)	(43,895)	(54,276)	(71,238)
Net loss	$ (16,551)	$ (7,482)	$ (14,359)	$ (15,089)	$ (19,632)	$ (13,962)	$ (12,612)	$ (20,539)	$ (53,481)	$ (66,745)	$ (75,096)
Basic and diluted net loss per share (in dollars per share)	$ (0.34)	$ (0.16)	$ (0.33)	$ (0.34)	$ (0.45)	$ (0.34)	$ (0.32)	$ (0.54)	$ (1.17)	$ (1.65)	$ (2.00)

401k Retirement Plan	12 Months Ended
401k Retirement Plan	Dec. 31, 2017
Retirement Benefits [Abstract]
401(k) Retirement Plan	401(k) Retirement Plan We have adopted a 401(k) plan. Beginning in 2017, our 401(k) retirement plan provides for an annual company match on employee contributions, initially set at a maximum of 4.0% of each participating employee’s eligible earnings, with a maximum company match of $4,000 per employee per year. All employees are eligible to participate, provided they meet the requirements of the plan.

401k Retirement Plan - Narrative (Details)	12 Months Ended
401k Retirement Plan - Narrative (Details)	Dec. 31, 2017 USD ($)
Retirement Benefits [Abstract]
Maximum percent of each employee's contributions matched by employer	4.00%
Maximum amount of each employee's contributions matched by employer	$ 4,000