CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net revenue	$ 169,030	$ 246,955	$ 418,931	$ 482,897
Costs and expenses:
Cost of revenue (exclusive of depreciation and amortization shown separately below)	11,825	14,975	28,672	29,240
Sales and marketing	96,289	122,045	233,586	246,361
Product development	53,969	54,566	121,082	112,641
General and administrative	26,402	30,932	69,938	62,224
Depreciation and amortization	12,582	12,240	24,940	24,116
Restructuring	3,312	0	3,312	0
Total costs and expenses	204,379	234,758	481,530	474,582
(Loss) income from operations	(35,349)	12,197	(62,599)	8,315
Other income, net	495	3,891	2,878	8,582
(Loss) income before income taxes	(34,854)	16,088	(59,721)	16,897
(Benefit from) provision for income taxes	(10,864)	3,785	(20,228)	3,229
Net (loss) income attributable to common stockholders	$ (23,990)	$ 12,303	$ (39,493)	$ 13,668
Net (loss) income per share attributable to common stockholders
Basic (in USD per share)	$ (0.33)	$ 0.16	$ (0.55)	$ 0.17
Diluted (in USD per share)	$ (0.33)	$ 0.16	$ (0.55)	$ 0.17
Weighted-average shares used to compute net (loss) income per share attributable to common stockholders
Basic (in shares)	72,413	75,601	71,980	78,620
Diluted (in shares)	72,413	78,530	71,980	81,742