CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	[1]
Income Statement [Abstract]
Net revenue	$ 223,074,000	$ 198,174,000
Costs and expenses:
Cost of revenue (exclusive of depreciation and amortization shown separately below)	14,732,000	16,914,000
Sales and marketing	119,641,000	108,532,000
Product development	51,493,000	39,871,000
General and administrative	32,007,000	27,166,000
Depreciation and amortization	10,028,000	10,151,000	[2]
Restructuring and integration	0	231,000
Total costs and expenses	227,901,000	202,865,000
Loss from operations	(4,827,000)	(4,691,000)
Other income, net	2,604,000	732,000
Loss before income taxes	(2,223,000)	(3,959,000)
Provision for income taxes	(63,000)	(67,000)
Net loss attributable to common stockholders	$ (2,286,000)	$ (4,026,000)	[2],[3]
Net loss per share attributable to common stockholders
Basic (in USD per share)	$ (0.03)	$ (0.05)
Diluted (in USD per share)	$ (0.03)	$ (0.05)
Weighted-average shares used to compute net loss per share attributable to common stockholders
Basic (in shares)	83,785	79,843
Diluted (in shares)	83,785	79,843

[1] As of January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Accordingly, the Company has recast certain amounts in the prior period presented. See Note 1 below for additional discussion.

[2] As of January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Accordingly, the Company has recast certain amounts in the prior period presented. See Note 1 below for additional discussion.Also as of January 1, 2018, the Company adopted Accounting Standards Update No. 2016-18, "Statement of Cash Flows (Subtopic 230): Restricted Cash," and recast the prior period presented. See Note 1 below for additional discussion.

[3] As of January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Accordingly, the Company has recast certain amounts in the prior period presented. See Note 1 below for additional discussion.