Goodwill and Other Intangible Assets - Intangible Assets - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	58,000,000		58,000,000		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	42,000,000		$ 42,000,000
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	31,000,000	$ 31,000,000	62,000,000	$ 61,000,000
Amortization expense for remainder 2020	59,000,000		59,000,000
Amortization expense for 2021	107,000,000		107,000,000
Amortization expense for 2022	58,000,000		58,000,000
Amortization expense for 2023	22,000,000		22,000,000
Amortization expense for 2024	11,000,000		11,000,000
Amortization expense for 2025	7,000,000		7,000,000
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