Goodwill and Intangible Assets, Net - Components of Intangible Assets with Definite Lives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Life (in years)	3 years 10 months 24 days
Gross Carrying Amount	$ 262	$ 253
Less: accumulated amortization	(206)	(173)
Intangible assets with definite lives, net	56	80
Accumulated Amortization	$ (206)	(173)
Trade Names and Trademarks
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Life (in years)	3 years 7 months 6 days
Gross Carrying Amount	$ 59	59
Less: accumulated amortization	(41)	(35)
Intangible assets with definite lives, net	18	24
Accumulated Amortization	$ (41)	(35)
Customer Lists and Supplier Relationships
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Life (in years)	4 years 6 months
Gross Carrying Amount	$ 104	98
Less: accumulated amortization	(83)	(65)
Intangible assets with definite lives, net	21	33
Accumulated Amortization	$ (83)	(65)
Subscriber Relationships
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Life (in years)	2 years 8 months 12 days
Gross Carrying Amount	$ 42	40
Less: accumulated amortization	(35)	(29)
Intangible assets with definite lives, net	7	11
Accumulated Amortization	$ (35)	(29)
Technology and Other
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Life (in years)	4 years 2 months 12 days
Gross Carrying Amount	$ 57	56
Less: accumulated amortization	(47)	(44)
Intangible assets with definite lives, net	10	12
Accumulated Amortization	$ (47)	$ (44)