Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 92,997	$ 79,790
Marketable investments (Note 4)	50,090	54,333
Accounts receivable, net	49,486	70,023
Deferred commissions	12,514	13,731
Prepaid expenses and other current assets	12,789	18,942
Total current assets	217,876	236,819
Property and equipment, net	23,342	25,249
Goodwill	76,551	76,169
Intangible assets, net	617	732
Other assets	7,756	6,231
Total assets	326,142	345,200
Current Liabilities:
Accounts payable	614	217
Accrued expenses and other current liabilities	34,300	49,629
Deferred revenue	143,023	145,207
Total current liabilities	177,937	195,053
Non-current liabilities	8,094	8,958
Total liabilities	186,031	204,011
Stockholders' Equity (Note 9):
Preferred stock, $0.01 par value Authorized - 500 shares; issued and outstanding - none
Common stock, $0.01 par value Authorized - 125,000 shares Issued - 22,564 and 22,432 shares as of June 30, 2018 and December 31, 2017, respectively Outstanding - 17,940 and 18,041 shares as of June 30, 2018 and December 31, 2017, respectively	226	224
Additional paid-in capital	189,554	181,910
Retained earnings	125,698	123,010
Treasury stock - 4,624 and 4,391 shares as of June 30, 2018 and December 31, 2017, respectively, at cost	(171,585)	(161,943)
Accumulated other comprehensive loss	(3,782)	(2,012)
Total stockholders’ equity	140,111	141,189
Total liabilities and stockholders’ equity	$ 326,142	$ 345,200