New Accounting Standards (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jan. 01, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction to income	$ (254)	$ (249)	$ (688)	$ (624)
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member
Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax impact of ASU 2016-13					$ 14
Financing Receivables and Unfunded Loan Commitments | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for expected credit losses					$ 65
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction to income			$ 15