Condensed Consolidated Balance Sheets (USD $) In Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 182,286	$ 107,717
Short-term investments	75	100,039
Receivable from collaboration partners (Note 2)	14,763	21,188
Prepaid expenses and other current assets	6,791	8,067
Total current assets	203,915	237,011
Property and equipment, net	796	862
Restricted cash	843	843
Other non-current assets	2,760	887
Total assets	208,314	239,603
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	6,285	3,229
Accrued expenses	24,201	21,399
Deferred revenue	59,762	59,153
Other current liabilities	459	5,193
Total current liabilities	90,707	88,974
Deferred revenue, net of current	113,390	141,507
Other non-current liabilities	1,296	1,438
Total liabilities	205,393	231,919
Contingencies (Note 11)
Stockholders' 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 34,906,744 at June 30, 2011 and 34,573,829 at December 31, 2010	349	346
Additional paid-in capital	231,948	218,786
Accumulated other comprehensive gain		2
Accumulated deficit	(229,376)	(211,450)
Total stockholders' equity	2,921	7,684
Total liabilities and stockholders' equity	$ 208,314	$ 239,603