Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 103,768	$ 112,644
Accounts receivable, net of allowances	40,189	37,867
Prepaid expenses and other current assets	10,039	5,756
Total current assets	153,996	156,267
Property and equipment, net	17,672	16,832
Goodwill	29,201	29,201
Intangible assets, net	7,373	7,076
Other assets	1,887	1,035
Total assets	210,129	210,411
Current liabilities:
Accounts payable	3,800	3,901
Accrued expenses and other current liabilities	20,117	20,691
Deferred revenue	66,884	62,945
Current portion of credit facility	2,746	2,719
Total current liabilities	93,547	90,256
Credit facility, net of current portion	1,955	2,653
Other liabilities	3,809	3,526
Total liabilities	99,311	96,435
Commitments and contingencies (Note 8)
Redeemable non-controlling interests (Note 6)	1,794	800
Stockholders' equity:
Common stock	4	4
Additional paid-in capital	311,340	297,420
Accumulated other comprehensive loss	(264)	(350)
Accumulated deficit	(202,056)	(183,898)
Total stockholders' equity	109,024	113,176
Total liabilities, redeemable non-controlling interests and stockholders' equity	$ 210,129	$ 210,411