New Accounting Standards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss	$ 123	$ 33	$ 24
Reduction to income	(885)	$ (829)	$ (774)
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax impact of ASU 2016-13				$ 14
Cumulative Effect, Period of Adoption, Adjustment | Financing Receivables And Unfunded Loan Commitments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss				$ 65
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction to income	$ 21