Stock Based Awards and Other Equity Instruments - Amount of Stock-Based Compensation Expense Related to Stock-Based Awards (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 25	$ 32	$ 51	$ 60
Income tax benefit from stock-based compensation	(5)	(8)	(12)	(14)
Total stock-based compensation expense, net of tax	20	24	39	46
Cost of Revenue
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense			1
Selling and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	4	6	7	11
Technology and Content
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	9	14	20	27
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 12	$ 12	$ 23	$ 22