Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 233,407	$ 60,232
Accounts receivable	2,622	2,211
Taxes receivable		1,240
Prepaid expenses and other current assets	1,700	968
Total current assets	237,729	64,651
Property and equipment, net	3,997	1,256
Developed technology, net	6,441	8,796
Goodwill	8,535	8,535
Other assets	68	60
Total assets	256,770	83,298
Current liabilities:
Accounts payable	1,234	1,507
Accrued expenses	4,827	5,003
Deferred revenue, short term	7,687	1,749
Total current liabilities	13,748	8,259
Deferred revenue, long term		991
Total liabilities	13,748	9,250
Commitments and contingencies (Note 9)
Stockholders' equity:
Common stock, par value $0.001; 60,000 shares authorized at September 30, 2012 and December 31, 2011; 24,290 and 17,582 shares issued and outstanding at September 30, 2012 and December 31, 2011, respectively	24	18
Additional paid-in capital	386,603	189,874
Accumulated other comprehensive loss	(7)	(4)
Accumulated deficit	(143,598)	(115,840)
Total stockholders' equity	243,022	74,048
Total liabilities and stockholders' equity	$ 256,770	$ 83,298