Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Costs and expenses:
Amortization of intangible assets	$ 33	$ 34	$ 32
Depreciation	93	82	79
Amortization adjustment	73	67	62
Stock-based compensation:
Stock-based compensation	124	118	96
Cost of Revenue
Stock-based compensation:
Stock-based compensation	1	1
Selling and Marketing
Stock-based compensation:
Stock-based compensation	23	21	21
Technology and Content
Stock-based compensation:
Stock-based compensation	55	51	40
General and Administrative
Stock-based compensation:
Stock-based compensation	45	45	35
Acquired Technology
Costs and expenses:
Amortization of intangible assets	10	8	8
Website Development Costs
Costs and expenses:
Depreciation	$ 63	$ 59	$ 54