Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Costs and expenses:
Amortization of intangible assets	$ 32	$ 36	$ 18
Depreciation	69	57	47
Amortization adjustment	53	46	34
Stock-based compensation:
Stock-based compensation	85	72	63
Selling and Marketing
Stock-based compensation:
Stock-based compensation	20	16	13
Technology and Content
Stock-based compensation:
Stock-based compensation	40	28	27
General and Administrative
Stock-based compensation:
Stock-based compensation	25	28	23
Acquired Technology
Costs and expenses:
Amortization of intangible assets	7	9	4
Website Development Costs
Costs and expenses:
Depreciation	$ 46	$ 37	$ 30