CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 37,445	$ 44,789
Short-term investments, available for sale	157,211	100,950
Receivables under collaboration agreements and other current assets	2,919	2,723
Total current assets	197,575	148,462
Property and equipment, net	2,239	1,771
Long-term investments, available for sale	65,282	0
Restricted cash	4,443	4,443
Total assets	269,539	154,676
Current liabilities:
Accounts payable	846	101
Accrued liabilities	7,439	7,955
Current portion of cease-use liability	441	416
Current portion of deferred rent	52	0
Current portion of deferred gain on sale of real estate	3,275	3,227
Total current liabilities	12,053	11,699
Deferred gain on sale of real estate	15,988	17,645
Deferred rent	1,942	1,982
Cease-use liability	2,451	2,680
Other liabilities	260	260
Total liabilities	32,694	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 75,919,009 as of June 30, 2014 and 67,351,195 as of December 31, 2013	76	67
Additional paid-in capital	1,027,881	886,101
Accumulated other comprehensive (loss) gain	(126)	5
Accumulated deficit	(790,986)	(765,763)
Total stockholders' equity	236,845	120,410
Total liabilities and stockholders' equity	$ 269,539	$ 154,676