Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue		$ 424	$ 391	$ 796	$ 743
Costs and expenses:
Cost of revenue	[1]	20	20	37	36
Selling and marketing	[2]	229	202	436	374
Technology and content	[2]	64	63	123	124
General and administrative	[2]	38	34	73	72
Depreciation		19	17	38	33
Amortization of intangible assets		8	8	16	15
Total costs and expenses:		378	344	723	654
Operating income		46	47	73	89
Other income (expense):
Interest expense		(4)	(3)	(7)	(6)
Interest income and other, net		2		3
Total other income (expense), net		(2)	(3)	(4)	(6)
Income before income taxes		44	44	69	83
Provision for income taxes		(17)	(10)	(29)	(19)
Net income		$ 27	$ 34	$ 40	$ 64
Earnings per share attributable to common stockholders (Note 4):
Basic		$ 0.19	$ 0.23	$ 0.28	$ 0.44
Diluted		$ 0.19	$ 0.23	$ 0.28	$ 0.44
Weighted average common shares outstanding (Note 4):
Basic		140,472	145,732	142,052	145,588
Diluted		140,937	147,060	142,827	146,982

[1] Excludes amortization as follows:

[2] Includes stock-based compensation expense as follows: