Derivative Financial Instruments - Carrying Amount and Cumulative Basis Adjustments for Hedge Accounting (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Hedged Items Currently Designated | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Assets/Liabilities	$ 11,018	$ 9,026
Cumulative Hedge Accounting Basis Adjustments	(307)	(64)
Hedged Items Currently Designated | Investment securities available-for-sale
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Assets/Liabilities	7,575	3,551
Cumulative Hedge Accounting Basis Adjustments	(210)	0
De-designated | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative Hedge Accounting Basis Adjustments	474	514
De-designated | Investment securities available-for-sale
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative Hedge Accounting Basis Adjustments	$ 20	$ 24