Organization and Significant Accounting Policies	12 Months Ended
Dec. 31, 2012
Organization and Significant Accounting Policies	Note 1—Organization and Significant Accounting Policies Organization We are a clinical-stage biopharmaceutical company committed to discovering, developing and commercializing products targeting inflammation, coagulopathies and disorders of the central nervous system. Our most clinically advanced products are derived from our proprietary PharmacoSurgery™ platform designed to improve clinical outcomes of patients undergoing ophthalmological, arthroscopic, urological and other surgical and medical procedures. Our efforts are devoted to conducting research and development of our products, to developing our patent portfolio and to raising equity capital. Basis of Presentation Our consolidated financial statements include the financial position and results of operations of Omeros and nura, inc., or nura, our wholly owned subsidiary. Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. 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 those estimates. Liquidity and Capital Resources We believe that our existing cash, cash equivalents and short-term investments and available capital under our at-the-market sales agreement and our committed equity line financing facility will be sufficient to fund our anticipated operating expenses, capital expenditures and note payments for at least the next 12 months. Our assumptions include our ability to raise capital under our $60.0 million at-the-market sales agreement with MLV & Co. LLC, or MLV, and under our committed equity line financing facility with Azimuth Opportunity, Ltd., or Azimuth. Our Azimuth facility includes terms that limit the amount of committed proceeds we can raise in specified periods, which terms are described in Note 9. Because the Azimuth facility will expire on June 1, 2013, taking into account its limitations, we believe that the amount of committed proceeds that we could raise before June 1, 2013 would be significantly less than $40.0 million. We are unable to estimate the actual amount as it depends on the price of our stock at the time we use the facility. If we do not raise additional capital, we may be required to delay, reduce the scope of, or eliminate our research and development programs, reduce our planned commercialization efforts or obtain funds through arrangements with collaborators or others that may require us to relinquish rights to certain products that we might otherwise seek to develop or commercialize independently, or enter into corporate collaborations at an earlier stage of development than we might otherwise choose. We expect our continuing operating losses to result in an increasing total amount of cash used in operations over the next several years. To meet our future capital requirements, we will need to finance our future cash needs through public or private equity offerings, debt financings or corporate collaboration and licensing arrangements. Except for our committed equity line financing facility with Azimuth which expires on June 1, 2013, we currently do not have any commitments for future external equity or debt funding. Additional equity or debt financing or corporate collaboration and licensing arrangements may not be available on acceptable terms, if at all. In addition, any future equity funding will dilute the ownership of our equity investors. Financial Instruments and Concentrations of Credit Risk Cash and cash equivalents, grant and other receivables, accounts payable, and accrued liabilities, which are recorded at 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 and short-term investments. 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 primarily in high quality securities such as money market mutual funds, certificates of deposit, and commercial paper. Cash and Cash Equivalents, Short-Term Investments, and Restricted Cash 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 are reported as a separate component of shareholders’ deficit, if necessary. Amortization, accretion, interest and dividends, realized gains and losses, and declines in value judged to be other-than-temporary are included in investment 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. This evaluation is dependent 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 consists of cash equivalents, the use of which is restricted and serves as collateral securing a letter of credit under a facility operating lease. Property and Equipment Property and equipment are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful life of the assets, which is generally three to ten years. Equipment financed under capital leases are amortized over the shorter of the useful lives of the related assets or the lease term. Impairment of Long-Lived Assets The carrying amount of long-lived assets, including property and equipment, are 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 that the asset is expected to generate. If the asset is considered to be impaired, the amount of any impairment will be reflected in the result of operations in the period of impairment. We have not recognized any impairment losses. Deferred Rent We recognize rent expense on a straight-line basis over the noncancelable term of our operating leases and, accordingly, record the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. We also record landlord-funded lease incentives, such as reimbursable leasehold improvements, as a deferred rent liability which is amortized as a reduction of rent expense over the noncancelable terms of our operating leases. Revenue Recognition Revenue is recognized when there is persuasive evidence that an arrangement exists, service has been provided, the price is fixed or determinable, and collection is reasonably assured. Our revenue relates to grant funding from third parties and revenue recognized in connection with funding from Vulcan Inc. and its affiliate, which we refer to collectively as Vulcan, and the Life Sciences Discovery Fund Authority, a granting agency of the State of Washington, or LSDF, for our G protein-coupled receptor, or GPCR, program. We recognize such funds as revenue when the related qualifying research and development expenses are incurred up to the limit of the approved funding amounts. Funds received in advance of services being provided are recorded as deferred revenue and recognized as revenue as research is performed. Research and Development Research and development costs are comprised primarily of costs for personnel, including salaries and benefits; occupancy; clinical studies performed by third parties; materials and supplies to support our clinical programs; contracted research; manufacturing; related consulting arrangements; and other expenses incurred to sustain our overall research and development programs. Research and development expenses are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are 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 products. Patent application costs are expensed as incurred as a component of general and administrative expense, as recoverability of such expenditures is uncertain. 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. A valuation allowance is established when it is not more likely than not that the deferred tax assets will be realized. Stock-Based Compensation Stock-based compensation expense is recognized for all share-based payments made to employees and directors based on estimated fair values. We use the straight-line method to allocate compensation cost to reporting periods over the optionees’ 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. The fair value of our stock options is calculated using the Black-Scholes option-pricing model. The Black-Scholes model requires judgmental assumptions including volatility, forfeiture rates and expected option life. If any of the assumptions used in the Black-Scholes model change significantly, stock-based compensation expense for new awards may differ materially from that recorded for existing awards. 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. Adoption of Standards In June 2011, the Financial Accounting Standards Board issued an Accounting Standards Update, or ASU, related to the presentation of comprehensive income that requires companies to present the components of net income and other comprehensive income either as one continuous statement or as two consecutive statements. It eliminated the option to present components of other comprehensive income as part of the statement of changes in shareholders’ equity. The standard does not change the items that must be reported in other comprehensive income, how such items are measured or when they must be reclassified to net income. This standard, which must be applied retroactively, was effective for interim and annual periods beginning after December 15, 2011. We adopted the standards on January 1, 2012 and now present a combined statement of operations and comprehensive loss in our accompanying financial statements.

Note 1—Organization and Significant Accounting Policies

Organization

We are a clinical-stage biopharmaceutical company committed to discovering, developing and commercializing products targeting inflammation, coagulopathies and disorders of the central nervous system. Our most clinically advanced products are derived from our proprietary PharmacoSurgery™ platform designed to improve clinical outcomes of patients undergoing ophthalmological, arthroscopic, urological and other surgical and medical procedures. Our efforts are devoted to conducting research and development of our products, to developing our patent portfolio and to raising equity capital.

Basis of Presentation

Our consolidated financial statements include the financial position and results of operations of Omeros and nura, inc., or nura, our wholly owned subsidiary.

Use of Estimates

The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. 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 those estimates.

Liquidity and Capital Resources

We believe that our existing cash, cash equivalents and short-term investments and available capital under our at-the-market sales agreement and our committed equity line financing facility will be sufficient to fund our anticipated operating expenses, capital expenditures and note payments for at least the next 12 months. Our assumptions include our ability to raise capital under our $60.0 million at-the-market sales agreement with MLV & Co. LLC, or MLV, and under our committed equity line financing facility with Azimuth Opportunity, Ltd., or Azimuth. Our Azimuth facility includes terms that limit the amount of committed proceeds we can raise in specified periods, which terms are described in Note 9. Because the Azimuth facility will expire on June 1, 2013, taking into account its limitations, we believe that the amount of committed proceeds that we could raise before June 1, 2013 would be significantly less than $40.0 million. We are unable to estimate the actual amount as it depends on the price of our stock at the time we use the facility. If we do not raise additional capital, we may be required to delay, reduce the scope of, or eliminate our research and development programs, reduce our planned commercialization efforts or obtain funds through arrangements with collaborators or others that may require us to relinquish rights to certain products that we might otherwise seek to develop or commercialize independently, or enter into corporate collaborations at an earlier stage of development than we might otherwise choose.

We expect our continuing operating losses to result in an increasing total amount of cash used in operations over the next several years. To meet our future capital requirements, we will need to finance our future cash needs through public or private equity offerings, debt financings or corporate collaboration and licensing arrangements. Except for our committed equity line financing facility with Azimuth which expires on June 1, 2013, we currently do not have any commitments for future external equity or debt funding. Additional equity or debt financing or corporate collaboration and licensing arrangements may not be available on acceptable terms, if at all. In addition, any future equity funding will dilute the ownership of our equity investors.

Financial Instruments and Concentrations of Credit Risk

Cash and cash equivalents, grant and other receivables, accounts payable, and accrued liabilities, which are recorded at 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 and short-term investments. 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 primarily in high quality securities such as money market mutual funds, certificates of deposit, and commercial paper.

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

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 are reported as a separate component of shareholders’ deficit, if necessary. Amortization, accretion, interest and dividends, realized gains and losses, and declines in value judged to be other-than-temporary are included in investment 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. This evaluation is dependent 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 consists of cash equivalents, the use of which is restricted and serves as collateral securing a letter of credit under a facility operating lease.

Property and Equipment

Property and equipment are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful life of the assets, which is generally three to ten years. Equipment financed under capital leases are amortized over the shorter of the useful lives of the related assets or the lease term.

Impairment of Long-Lived Assets

The carrying amount of long-lived assets, including property and equipment, are 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 that the asset is expected to generate. If the asset is considered to be impaired, the amount of any impairment will be reflected in the result of operations in the period of impairment. We have not recognized any impairment losses.

Deferred Rent

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

Revenue Recognition

Revenue is recognized when there is persuasive evidence that an arrangement exists, service has been provided, the price is fixed or determinable, and collection is reasonably assured.

Our revenue relates to grant funding from third parties and revenue recognized in connection with funding from Vulcan Inc. and its affiliate, which we refer to collectively as Vulcan, and the Life Sciences Discovery Fund Authority, a granting agency of the State of Washington, or LSDF, for our G protein-coupled receptor, or GPCR, program. We recognize such funds as revenue when the related qualifying research and development expenses are incurred up to the limit of the approved funding amounts. Funds received in advance of services being provided are recorded as deferred revenue and recognized as revenue as research is performed.

Research and Development

Research and development costs are comprised primarily of costs for personnel, including salaries and benefits; occupancy; clinical studies performed by third parties; materials and supplies to support our clinical programs; contracted research; manufacturing; related consulting arrangements; and other expenses incurred to sustain our overall research and development programs. Research and development expenses are expensed as incurred.

Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are 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 products. Patent application costs are expensed as incurred as a component of general and administrative expense, as recoverability of such expenditures is uncertain.

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. A valuation allowance is established when it is not more likely than not that the deferred tax assets will be realized.

Stock-Based Compensation

Stock-based compensation expense is recognized for all share-based payments made to employees and directors based on estimated fair values. We use the straight-line method to allocate compensation cost to reporting periods over the optionees’ 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. The fair value of our stock options is calculated using the Black-Scholes option-pricing model. The Black-Scholes model requires judgmental assumptions including volatility, forfeiture rates and expected option life. If any of the assumptions used in the Black-Scholes model change significantly, stock-based compensation expense for new awards may differ materially from that recorded for existing awards.

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.

Adoption of Standards

In June 2011, the Financial Accounting Standards Board issued an Accounting Standards Update, or ASU, related to the presentation of comprehensive income that requires companies to present the components of net income and other comprehensive income either as one continuous statement or as two consecutive statements. It eliminated the option to present components of other comprehensive income as part of the statement of changes in shareholders’ equity. The standard does not change the items that must be reported in other comprehensive income, how such items are measured or when they must be reclassified to net income. This standard, which must be applied retroactively, was effective for interim and annual periods beginning after December 15, 2011. We adopted the standards on January 1, 2012 and now present a combined statement of operations and comprehensive loss in our accompanying financial statements.