Goodwill and Other Intangible Assets - Intangible Assets - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired during the year			$ 0
Finite-lived intangible assets, gross	$ 1,000,000		1,000,000		$ 1,000,000
Net, intangible asset not subject to amortization	55,000,000		55,000,000		63,000,000
Gross carrying amount of capitalized software	1,100,000,000		1,100,000,000		1,100,000,000
Capitalized computer software, net	270,000,000		270,000,000		321,000,000
Capitalized computer software, development stage costs	13,000,000		$ 13,000,000
Capitalized Internal Use Software, Significant System Conversions
Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization period			3 years
Capitalized Internal Use Software
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible asset, residual value	0		$ 0
Amortization expense	34,000,000	$ 30,000,000	96,000,000	$ 91,000,000
Amortization expense for remainder 2020	30,000,000		30,000,000
Amortization expense for 2021	111,000,000		111,000,000
Amortization expense for 2022	69,000,000		69,000,000
Amortization expense for 2023	34,000,000		34,000,000
Amortization expense for 2024	11,000,000		11,000,000
Amortization expense for 2025	9,000,000		9,000,000
Amortization expense thereafter	6,000,000		6,000,000
Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived intangible assets, net	$ 1,000,000		$ 1,000,000		$ 1,000,000
Maximum | Capitalized Internal Use Software, Significant System Conversions
Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization period			10 years
Minimum [Member] | Capitalized Internal Use Software, Significant System Conversions
Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization period			8 years