Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 167,919	$ 187,661
Accounts receivable	5,652	4,713
Other current assets	3,023	1,534
Total Current Assets	176,594	193,908
Restricted Investments	7,250
Property and Equipment, net of accumulated depreciation and amortization of $17,024 and $16,708	3,088	3,397
Patent Costs, net of accumulated amortization of $1,534 and $2,626	4,883	4,913
Other assets	1,525	2,775
Total Assets	193,340	204,993
Current Liabilities:
Accounts payable	7,073	7,532
Accrued employee compensation	1,520	2,741
Long-term debt, current portion	90	89
Warrant liability	91,077	65,193
Deferred revenue	3,884	3,304
Other liabilities	15	27
Total Current Liabilities	103,659	78,886
Commitments and Contingencies
Long-term debt	1,645	1,668
Other long-term liabilities	755	760
Total Liabilities	106,059	81,314
Shareholders' Equity:
Preferred stock, $.0001 par value, 3,333,333 shares authorized; none issued and outstanding
Common stock, $.0001 par value, 50,000,000 shares authorized; 31,888,949 and 31,703,817 issued and outstanding	3	3
Additional paid-in capital	560,613	554,927
Deficit accumulated during the development stage	(473,335)	(431,251)
Total Shareholders' Equity	87,281	123,679
Total Liabilities and Shareholders' Equity	$ 193,340	$ 204,993