Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 117,841	$ 114,989
Short-term investments	77,915	82,020
Accounts receivable—net of allowance for doubtful accounts of $1,738 and $1,328 at March 31, 2016 and December 31, 2015, respectively	49,790	60,793
Prepaid expenses and other current assets	10,654	8,424
Total current assets	256,200	266,226
Property and equipment, net	27,551	21,862
Intangible assets, net	22,504	23,805
Goodwill	59,465	59,465
Other assets	6,377	6,040
Total assets	372,097	377,398
Current liabilities:
Accounts payable	4,494	2,866
Accrued expenses	27,508	37,287
Deferred revenue	31,585	31,426
Total current liabilities	63,587	71,579
Long-term liabilities:
Deferred revenue	17,153	15,133
Other long-term liabilities	3,156	2,763
Total liabilities	$ 83,896	$ 89,475
Commitments and contingencies (Note 9)
Redeemable noncontrolling interest	$ 338	$ 457
Stockholders’ equity:
Preferred stock, $0.01 par value per share—10,000 shares authorized
Common stock, $0.01 par value per share—240,000 shares authorized, 36,568 and 36,224 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 366	$ 362
Additional paid-in capital	448,943	437,137
Accumulated other comprehensive loss	(580)	(858)
Accumulated deficit	(160,866)	(149,175)
Total stockholders’ equity	287,863	287,466
Total liabilities, redeemable noncontrolling interest and stockholders’ equity	$ 372,097	$ 377,398