Borrowed Funds (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Borrowed funds	$ 65,384	$ 58,713
Parent Company
Debt Instrument [Line Items]
Borrowed funds	19,212	13,103
Parent Company | Senior debt
Debt Instrument [Line Items]
Borrowed funds	17,480	11,374
Basis adjustments - Fair value accounting hedges	(869)
Parent Company | Subordinated debt
Debt Instrument [Line Items]
Borrowed funds	1,526	1,524
Basis adjustments - Fair value accounting hedges	(70)
Subsidiaries
Debt Instrument [Line Items]
Borrowed funds	42,341	41,936
Subsidiaries | Senior debt
Debt Instrument [Line Items]
Borrowed funds	4,525	5,283
Basis adjustments - Fair value accounting hedges	(249)
Subsidiaries | Subordinated debt
Debt Instrument [Line Items]
Borrowed funds	3,816	$ 4,578
Basis adjustments - Fair value accounting hedges	$ (229)