Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 33,009	$ 69,482
Marketable securities	154,572	139,518
Interest receivable	402	307
Accounts receivable	2,567	2,521
Prepaid expenses	588	754
Total current assets	191,138	212,582
Marketable securities, non-current	1,003
Property and equipment, net	3,176	2,916
Goodwill	1,585	1,585
Other assets	146	152
Total assets	197,048	217,235
Current liabilities:
Accounts payable and accrued liabilities	3,111	8,229
Accrued compensation and employee benefits	1,722	2,748
Deferred revenues	5,261	9,120
Total current liabilities	10,094	20,097
Deferred revenues, non-current	7,334	4,699
Build-to-suit lease obligation	213
Total liabilities	$ 17,641	$ 24,796
Commitments and contingencies
Stockholders' equity:
Common stock, $0.01 par value; 160,000,000 shares authorized, 70,400,036 and 70,354,608 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 704	$ 703
Additional paid-in capital	564,367	560,989
Accumulated deficit	(385,747)	(369,253)
Accumulated other comprehensive income	83
Total stockholders' equity	179,407	192,439
Total liabilities and stockholders' equity	$ 197,048	$ 217,235