CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 47,234	$ 104,287
Short-term investments	49,576	13,869
Accounts receivable, net of allowance for doubtful accounts of $628 and $550 at December 31, 2015 and December 31, 2014, respectively	42,674	34,676
Prepaid expenses and other current assets	4,809	4,018
Total current assets	144,293	156,850
Long-term investments	2,094	22,220
Property and equipment-net	6,572	3,978
Intangible assets-net	1,261	2,132
Goodwill	5,475	5,475
Other assets	1,419	1,187
TOTAL ASSETS	161,114	191,842
Current liabilities:
Accounts payable	2,551	1,137
Accrued expenses	19,196	21,169
Deferred revenue-current	55,978	44,096
TOTAL CURRENT LIABILITIES	77,725	66,402
Long-term liabilities:
Deferred revenue-noncurrent	13,897	10,078
Other long-term liabilities	1,353	268
TOTAL LIABILITIES	$ 92,975	$ 76,748
Commitments and contingencies (Note 13)
Stockholders' equity:
Common stock, $0.0001 par value, 300,000,000 shares authorized, 81,326,237 shares and 76,153,844 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	$ 8	$ 8
Additional paid-in capital	343,336	305,809
Accumulated deficit	(275,205)	(190,723)
TOTAL STOCKHOLDERS' EQUITY (DEFICIT)	68,139	115,094
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 161,114	$ 191,842