Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 40,404	$ 32,533
Short-term marketable securities	56,585	62,410
Accounts receivable (net of allowance for doubtful accounts; 2016—$4,508, 2015—$3,988)	35,179	37,164
Prepaid expenses and other current assets	13,796	10,843
Total current assets	145,964	142,950
Property and equipment, net	45,688	39,746
Other assets	9,462	1,921
Total assets	201,114	184,617
Current liabilities:
Accounts payable	2,864	8,585
Accrued compensation and employee benefits	27,900	22,239
Accrued license fees		2,287
Accrued expenses and other current liabilities	10,180	8,922
Deferred revenues		431
Other current liabilities	231	208
Total current liabilities	41,175	42,672
Other liabilities	3,834	2,410
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value, 5,000,000 shares authorized, no shares issued and outstanding
Common stock, $0.0001 par value; 100,000,000 shares authorized, 34,893,329 and 33,861,759 shares issued and 33,831,998 and 32,800,428 shares outstanding at December 31, 2016 and 2015, respectively	3	3
Additional paid- in capital	427,102	395,059
Accumulated other comprehensive income	1,198	2,752
Accumulated deficit	(242,088)	(228,169)
Treasury stock, at cost, 1,061,331 shares at December 31, 2016 and 2015	(30,110)	(30,110)
Total stockholders' equity	156,105	139,535
Total liabilities and stockholders' equity	$ 201,114	$ 184,617