Derivative Financial Instruments - Carrying Amount and Cumulative Basis Adjustments for Hedge Accounting (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Derivatives designated as hedging instruments | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	$ 9,026	$ 10,519
Active	(64)	3
Derivatives designated as hedging instruments | Investment securities available-for-sale
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	3,551	2,330
Active	0	2
Derivatives not designated as hedging instruments | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	514	688
Derivatives not designated as hedging instruments | Investment securities available-for-sale
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Assets	$ 24	$ 43