Borrowed Funds (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Borrowed funds	$ 35,984	$ 30,784
Parent Company
Debt Instrument [Line Items]
Borrowed funds	10,426	11,351
Parent Company | Senior debt
Debt Instrument [Line Items]
Borrowed funds	8,641	10,369
Basis adjustments - Fair value accounting hedges	(462)
Parent Company | Subordinated debt
Debt Instrument [Line Items]
Borrowed funds	1,580	777
Basis adjustments - Fair value accounting hedges	(9)
Subsidiaries
Debt Instrument [Line Items]
Borrowed funds	21,419	16,306
Subsidiaries | Senior debt
Debt Instrument [Line Items]
Borrowed funds	5,717	10,292
Basis adjustments - Fair value accounting hedges	(128)
Subsidiaries | Subordinated debt
Debt Instrument [Line Items]
Borrowed funds	5,702	$ 6,014
Basis adjustments - Fair value accounting hedges	$ (117)