Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 70,136	$ 107,717
Short-term investments	74,996	100,039
Receivable from collaboration partners	12,545	21,188
Prepaid expenses and other current assets	10,512	8,067
Total current assets	168,189	237,011
Property and equipment, net	720	862
Restricted cash	5,489	843
Other non-current assets	719	887
Total assets	175,117	239,603
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	5,588	3,229
Accrued expenses	24,014	21,399
Deferred revenue	59,762	59,153
Other current liabilities	270	5,193
Total current liabilities	89,634	88,974
Deferred revenue, net of current	83,509	141,507
Other non-current liabilities	653	1,438
Total liabilities	173,796	231,919
Commitments and 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 of 35,731,838 at December 31, 2011 and 34,573,829 at December 31, 2010	357	346
Additional paid-in capital	251,242	218,786
Accumulated other comprehensive gain	13	2
Accumulated deficit	(250,291)	(211,450)
Total stockholders' equity	1,321	7,684
Total liabilities and stockholders' equity	$ 175,117	$ 239,603