Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 77,481	$ 91,297
Marketable securities	21,794	36,679
Prepaid expenses and other current assets	2,011	922
Deferred tax assets	1,247	1,246
Total current assets	102,533	130,144
Property and equipment, net	3,818	3,565
Restricted cash	571	571
Deferred tax assets, net of current portion	2,706	2,706
Other assets	1,624	22
Total assets	111,252	137,008
Current liabilities:
Accounts payable	3,038	3,308
Accrued expenses	3,586	1,708
Income taxes payable	5,141	4,875
Deferred revenue	25,072	25,072
Deferred rent	104	85
Restricted stock liability	38	65
Total current liabilities	36,979	35,113
Deferred revenue, net of current portion	45,103	57,639
Deferred rent, net of current portion	288	343
Restricted stock liability, net of current portion	10	15
Commitments and contingencies
Stockholders' deficit:
Common stock, $0.001 par value; 78,300,000 authorized at December 31, 2012 and June 30, 2013, respectively, and 3,616,101 and 3,770,266 shares issued and outstanding at December 31, 2012 and June 30, 2013, respectively	4	3
Additional paid-in capital	2,836	2,012
Accumulated other comprehensive loss	(5)	(2)
Accumulated deficit	(89,885)	(74,037)
Total stockholders' deficit	(87,050)	(72,024)
Total liabilities, convertible preferred stock, and stockholders' deficit	111,252	137,008
Series A Preferred Stock [Member]
Current liabilities:
Convertible preferred stock	32,940	32,940
Series B Preferred Stock [Member]
Current liabilities:
Convertible preferred stock	5,681	5,681
Series C Preferred Stock [Member]
Current liabilities:
Convertible preferred stock	$ 77,301	$ 77,301