Liquidity	9 Months Ended
Sep. 30, 2011
Liquidity [Abstract]
Liquidity	Note 9. Liquidity Since its inception in 1980 through September 30, 2011 the Company has incurred losses of approximately $308.6 million, substantially all of which resulted from expenditures related to research and development, general and administrative charges and acquired in-process research and development resulting from two acquisitions. The Company has not generated any material revenue from product sales to date, and there can be no assurance that revenue from product sales will be achieved. The Company expects to incur operating losses over the next several years. At September 30, 2011, cash and cash equivalents were $46.4 million, compared to $33.6 million at December 31, 2010. The Company's principal sources of liquidity have been equity financings and revenue from its U.S. government research contracts. The Company's principal uses of cash have been research and development expenses, general and administrative expenses and other working capital requirements. In the periods presented, substantially all of the revenue generated by the Company was derived from research contracts with the U.S. government. As of September 30, 2011, the Company had ongoing contracts with the U.S. government pursuant to which it is entitled to receive up to an aggregate of $126.5 million for development of its product candidates, of which $39.6 million had been recognized as revenue and $86.9 million relates to development that has not yet been completed and has not been billed or recognized as revenue. Additionally, the Company is potentially eligible for an amount up to approximately $161.5 million of the potential aggregate total award of $288.0 million if the U.S. government exercises all its options on the July 2010 Ebola and Marburg agreement. See Note 5 — "U.S. Government Contracts" for additional information. In January and August 2009, the Company sold shares of its common stock and also issued warrants to purchase shares of its common stock in offerings registered under the Securities Act of 1933 (the "Securities Act"). In April 2011, the Company sold 23.0 million shares of its common stock at the price of $1.50 per share in an offering registered under the Securities Act. The offering generated gross proceeds of $34.5 million. See Note 10 — "Equity Financings" for more information.

Liquidity

9 Months Ended

Sep. 30, 2011

Note 9. Liquidity

Since its inception in 1980 through September 30, 2011 the Company has incurred losses of approximately $308.6 million, substantially all of which resulted from expenditures related to research and development, general and administrative charges and acquired in-process research and development resulting from two acquisitions. The Company has not generated any material revenue from product sales to date, and there can be no assurance that revenue from product sales will be achieved. The Company expects to incur operating losses over the next several years.

At September 30, 2011, cash and cash equivalents were $46.4 million, compared to $33.6 million at December 31, 2010. The Company's principal sources of liquidity have been equity financings and revenue from its U.S. government research contracts. The Company's principal uses of cash have been research and development expenses, general and administrative expenses and other working capital requirements.

In the periods presented, substantially all of the revenue generated by the Company was derived from research contracts with the U.S. government. As of September 30, 2011, the Company had ongoing contracts with the U.S. government pursuant to which it is entitled to receive up to an aggregate of $126.5 million for development of its product candidates, of which $39.6 million had been recognized as revenue and $86.9 million relates to development that has not yet been completed and has not been billed or recognized as revenue. Additionally, the Company is potentially eligible for an amount up to approximately $161.5 million of the potential aggregate total award of $288.0 million if the U.S. government exercises all its options on the July 2010 Ebola and Marburg agreement. See Note 5 — "U.S. Government Contracts" for additional information.

In January and August 2009, the Company sold shares of its common stock and also issued warrants to purchase shares of its common stock in offerings registered under the Securities Act of 1933 (the "Securities Act"). In April 2011, the Company sold 23.0 million shares of its common stock at the price of $1.50 per share in an offering registered under the Securities Act. The offering generated gross proceeds of $34.5 million. See Note 10 — "Equity Financings" for more information.