Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 30,705	$ 32,533
Short-term marketable securities	55,671	62,410
Accounts receivable (net of allowance for doubtful accounts; 2016—$3,996, 2015—$3,988)	38,829	37,164
Prepaid expenses and other current assets	11,352	10,843
Total current assets	136,557	142,950
Property and equipment, net	39,311	39,746
Other assets	1,853	1,921
Total assets	177,721	184,617
Current liabilities:
Accounts payable	4,702	8,585
Accrued compensation and employee benefits	20,058	22,239
Accrued license fees	2,495	2,287
Accrued expenses and other current liabilities	9,599	8,922
Deferred revenues	374	431
Other current liabilities	208	208
Total current liabilities	37,436	42,672
Other liabilities	$ 2,874	$ 2,410
Commitments and contingencies
Stockholders' equity:
Common stock	$ 3	$ 3
Additional paid- in capital	397,337	395,059
Accumulated other comprehensive income	4,701	2,752
Accumulated deficit	(234,520)	(228,169)
Treasury stock, at cost	(30,110)	(30,110)
Total stockholders' equity	137,411	139,535
Total liabilities and stockholders' equity	$ 177,721	$ 184,617