Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income Statement [Abstract]
Revenue (Note 4)		$ 1,615	$ 1,556		$ 1,480
Costs and expenses:
Cost of revenue	[1],[2]	86	72		71
Selling and marketing	[2]	778	849		756
Technology and content	[2]	275	243		243
General and administrative	[2]	177	157		143
Depreciation		82	79		69
Amortization of intangible assets		34	32		32
Total costs and expenses		1,432	1,432		1,314
Operating income		183	124		166
Other income (expense):
Interest expense		(12)	(15)		(12)
Interest income and other, net (Note 19)		2	1		(3)
Total other income (expense), net		(10)	(14)		(15)
Income before income taxes		173	110		151
Provision for income taxes (Note 11)		(60)	(129)	[3]	(31)
Net income (loss)		$ 113	$ (19)		$ 120
Earnings (loss) per share attributable to common stockholders (Note 5):
Basic		$ 0.82	$ (0.14)		$ 0.83
Diluted		$ 0.81	$ (0.14)		$ 0.82
Weighted average common shares outstanding (Note 5):
Basic		138,116	140,445		145,443
Diluted		140,375	140,445		146,893

[1] Excludes amortization expense as follows:

[2] Includes stock-based compensation expense as follows

[3] The year ended December 31, 2017 reflects $67 million of Transition Tax and $6 million of tax expense recorded due to the remeasurement of net deferred tax assets related to the 2017 Tax Act enacted on December 22, 2017. Refer to “Note 11: Income Taxes” for further information.