Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash	$ 83,508	$ 86,553
Accounts receivables, net of allowance for doubtful accounts of $728 and $730 at March 31, 2016 and December 31, 2015, respectively	29,817	44,164
Prepaid expenses and other current assets	6,618	6,148
Total current assets	119,943	136,865
Property and equipment, net	7,611	7,532
Goodwill	74,943	74,565
Intangible assets, net	10,802	11,385
Other assets	481	214
Total assets	213,780	230,561
Current liabilities:
Accounts payable	1,657	2,038
Accrued expenses	14,424	24,707
Deferred revenue, current portion	90,081	87,917
Other current liabilities	767	1,105
Total current liabilities	106,929	115,767
Deferred revenue, non-current portion	41,776	42,400
Other long-term liabilities	4,460	4,319
Total liabilities	$ 153,165	$ 162,486
Stockholders' equity:
Preferred stock, $0.01 par value per share; 10,000,000 shares authorized at March 31, 2016 and December 31, 2015; 0 shares issued at March 31, 2016 and December 31, 2015
Common stock, $0.01 par value; 100,000,000 shares authorized at March 31, 2016 and December 31, 2015; 42,277,059 and 41,942,026 shares issued at March 31, 2016 and December 31, 2015, respectively; 41,875,433 and 41,540,400 shares outstanding at March 31, 2016 and December 31, 2015, respectively	$ 419	$ 415
Additional paid-in-capital	419,640	411,524
Accumulated deficit	(355,918)	(340,338)
Treasury stock, at cost, 401,626 shares at March 31, 2016 and December 31, 2015	(3,526)	(3,526)
Total stockholders' equity	60,615	68,075
Total liabilities and stockholders' equity	$ 213,780	$ 230,561