Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 62,812	$ 12,357
Other receivable	480
Income tax receivable	57	61
Prepaid expenses & other current assets	1,706	2,140
Total current assets	65,055	14,558
Property and equipment, net	2,439	2,825
Restricted cash	700	700
Total assets	68,194	18,083
Current liabilities:
Accounts payable and accrued expenses	2,548	1,958
Deferred revenue	3,069	3,475
Total current liabilities	5,617	5,433
Deferred lease obligation	1,009	1,139
Commitments and contingencies (Note 13)
Convertible Preferred stock; $0.001 par value; zero shares and 29,402,200 shares authorized at June 30, 2014 and December 31, 2013, respectively; zero shares and 29,186,929 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively; aggregate liquidation preference of zero and $65,969 at June 30, 2014 and December 31, 2013, respectively	0	65,586
Stockholders' (deficit) equity:
Preferred stock; $0.001 par value; 5,000,000 shares and zero shares authorized at June 30, 2014 and December 31, 2013, respectively, zero shares issued and outstanding at June 30, 2014 and December 31, 2013	0	0
Common stock; $0.001 par value; 100,000,000 shares and 50,000,000 shares authorized at June 30, 2014 and December 31, 2013, respectively, 22,638,414 shares and 4,288,243 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	23	4
Additional paid-in capital	131,029	8,377
Accumulated deficit	(69,484)	(62,456)
Total stockholders' (deficit) equity	61,568	(54,075)
Total liabilities, convertible preferred stock and stockholders' (deficit) equity	$ 68,194	$ 18,083