CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 105,532	$ 44,789
Short-term investments, available for sale	114,330	100,950
Receivables under collaboration agreements and other current assets	1,873	2,723
Total current assets	221,735	148,462
Property and equipment, net	1,798	1,771
Long-term investments, available for sale	51,320	0
Restricted cash	4,443	4,443
Total assets	279,296	154,676
Current liabilities:
Accounts payable	818	101
Accrued liabilities	6,111	7,955
Current portion of cease-use liability	428	416
Current portion of deferred gain on sale of real estate	3,251	3,227
Total current liabilities	10,608	11,699
Deferred gain on sale of real estate	16,817	17,645
Deferred rent	1,988	1,982
Cease-use liability	2,566	2,680
Other liabilities	260	260
Total liabilities	32,239	34,266
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value; 110,000,000 shares authorized; issued and outstanding shares were 75,858,681 as of March 31, 2014 and 67,351,195 as of December 31, 2013	76	67
Additional paid-in capital	1,024,780	886,101
Accumulated other comprehensive (loss) gain	(194)	5
Accumulated deficit	(777,605)	(765,763)
Total stockholders' equity	247,057	120,410
Total liabilities and stockholders' equity	$ 279,296	$ 154,676