Description of Business, Basis of Presentation, and Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Jan. 01, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Troubled debt restructuring threshold	10.00%
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction to retained earnings	$ 1,599		$ 4,278
Increase to allowance for credit losses	$ 3,267		$ 3,283		$ 1,263
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life	3 years
Minimum | Capitalized software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life	30 years
Maximum | Capitalized software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life	5 years
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to allowance for credit losses					$ 1,346
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Phase-in of capital impact of Accounting Standards Update 2016-13	25.00%
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction to retained earnings				$ 1,000
Increase to allowance for credit losses		$ 1,300