CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 79,605	$ 54,043
Short-term investments	2,600	36,184
Accounts receivable, net of allowance for doubtful accounts of $431 and $433 at September 30, 2017 and December 31, 2016, respectively	47,732	43,755
Prepaid expenses and other current assets	5,440	6,131
TOTAL CURRENT ASSETS	135,377	140,113
Property and equipment-net	8,781	5,503
Intangible assets-net	200	645
Goodwill	5,475	5,475
Other assets	1,809	1,370
TOTAL ASSETS	151,642	153,106
Current liabilities:
Accounts payable	2,609	701
Accrued expenses	22,452	21,674
Deferred revenue-current	75,950	68,153
TOTAL CURRENT LIABILITIES	101,011	90,528
Long-term liabilities:
Deferred revenue-noncurrent	25,063	19,923
Other long-term liabilities	1,928	1,838
TOTAL LIABILITIES	128,002	112,289
Commitments and contingencies (Note 12)
Stockholders' equity:
Common stock, $0.0001 par value, 300,000,000 shares authorized, 96,048,823 shares and 89,066,031 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	10	9
Additional paid-in capital	414,457	383,193
Accumulated deficit	(390,827)	(342,385)
TOTAL STOCKHOLDERS' EQUITY	23,640	40,817
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 151,642	$ 153,106