Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 105,086	$ 194,494
Marketable securities	88,894	34,982
Prepaid expenses and other, current	10,654	6,998
Total current assets	204,634	236,474
Property and equipment, net	5,000	5,153
Prepaid expenses and other, long-term	2,674	6,846
Restricted cash	4,316	4,317
Total assets	216,624	252,790
Current liabilities:
Accounts payable	23,970	20,035
Accrued expenses	19,760	17,426
Total current liabilities	43,730	37,461
Deferred rent	5,502	5,505
Total liabilities	49,232	42,966
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock - $.0001 par value; 100,000,000 shares authorized; 36,963,278 shares issued and outstanding at March 31, 2017 and 36,826,010 issued and outstanding at December 31, 2016	4	4
Additional paid-in capital	1,036,825	1,006,344
Receivables from the exercise of options	(11)
Accumulated other comprehensive loss	(50)	(13)
Accumulated deficit	(869,376)	(796,511)
Total stockholders' equity	167,392	209,824
Total liabilities and stockholders' equity	$ 216,624	$ 252,790