Condensed Consolidated Balance Sheets (USD $) In Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 88,371	$ 107,717
Short-term investments	74,979	100,039
Receivable from collaboration partners	14,137	21,188
Prepaid expenses and other current assets	4,964	8,067
Total current assets	182,451	237,011
Property and equipment, net	677	862
Restricted cash	843	843
Other non-current assets	4,296	887
Total assets	188,267	239,603
LIABILITIES AND STOCKHOLDERS' (DEFICIT) EQUITY
Accounts payable	5,311	3,229
Accrued expenses	27,146	21,399
Deferred revenue	59,762	59,153
Other current liabilities	839	5,193
Total current liabilities	93,058	88,974
Deferred revenue, net of current	98,450	141,507
Other non-current liabilities	628	1,438
Total liabilities	192,136	231,919
Contingencies (Note 10)
Stockholders' (deficit) equity:
Preferred stock, $0.01 par value per share; 1,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.01 par value per share; 50,000,000 shares authorized; issued and outstanding shares of 34,910,494 at September 30, 2011 and 34,573,829 at December 31, 2010	349	346
Additional paid-in capital	235,191	218,786
Accumulated other comprehensive gain	11	2
Accumulated deficit	(239,420)	(211,450)
Total stockholders' (deficit) equity	(3,869)	7,684
Total liabilities and stockholders' (deficit) equity	$ 188,267	$ 239,603