Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 39,834	$ 42,007
Short-term investments	84,275	36,741
Accounts receivable, net of allowance for doubtful accounts of $492 and $122	50,763	58,587
Prepaid expenses and other current assets	5,776	5,440
Total current assets	180,648	142,775
Long-term assets
Property and equipment, net of accumulated depreciation of $19,897 and $17,091	12,300	12,827
Long-term investments		38,446
Other long-term assets	971	734
Total assets	193,919	194,782
Current liabilities
Accounts payable	4,550	3,574
Accrued payroll and other expenses	14,015	14,073
Deferred revenue	93,450	97,885
Deferred rent	843	799
Capital leases	32	43
Total current liabilities	112,890	116,374
Long-term liabilities
Deferred revenue, net of current portion	3,868	2,254
Deferred rent, net of current portion	3,927	4,360
Capital leases, net of current portion	36	51
Asset retirement obligation	187	175
Total liabilities	120,908	123,214
Commitments and contingencies (Note 8)
Stockholders’ equity
Class A and Class B Common stock	4	4
Additional paid-in capital	287,038	271,982
Accumulated other comprehensive loss	(147)	(94)
Accumulated deficit	(213,884)	(200,324)
Total stockholders’ equity	73,011	71,568
Total liabilities and stockholders' equity	$ 193,919	$ 194,782