Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 29,279	$ 42,007
Short-term investments	106,249	36,741
Accounts receivable, net of allowance for doubtful accounts of $305 and $122	46,136	58,587
Prepaid expenses and other current assets	5,530	5,440
Total current assets	187,194	142,775
Long-term assets
Property and equipment, net of accumulated depreciation of $20,982 and $17,091	11,168	12,827
Long-term investments		38,446
Other long-term assets	944	734
Total assets	199,306	194,782
Current liabilities
Accounts payable	3,995	3,574
Accrued payroll and other expenses	14,568	14,073
Deferred revenue	96,609	97,885
Deferred rent	868	799
Capital leases	27	43
Total current liabilities	116,067	116,374
Long-term liabilities
Deferred revenue, net of current portion	3,602	2,254
Deferred rent, net of current portion	3,709	4,360
Capital leases, net of current portion	31	51
Asset retirement obligation	194	175
Total liabilities	123,603	123,214
Commitments and contingencies (Note 8)
Stockholders’ equity
Class A and Class B Common stock	4	4
Additional paid-in capital	294,848	271,982
Accumulated other comprehensive loss	(94)	(94)
Accumulated deficit	(219,055)	(200,324)
Total stockholders’ equity	75,703	71,568
Total liabilities and stockholders' equity	$ 199,306	$ 194,782