Borrowed Funds (FHLB Borrowings, Senior Debt and Subordinated Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Borrowed funds	$ 65,384	$ 58,713
Total FHLB, Senior and Sub Debt	61,553	55,039
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
Parent Company | Senior debt | Minimum
Debt Instrument [Line Items]
Interest rate	1.15%
Parent Company | Senior debt | Maximum
Debt Instrument [Line Items]
Interest rate	6.04%
Parent Company | Subordinated debt
Debt Instrument [Line Items]
Borrowed funds	$ 1,526	1,524
Parent Company | Subordinated debt | Minimum
Debt Instrument [Line Items]
Interest rate	3.90%
Parent Company | Subordinated debt | Maximum
Debt Instrument [Line Items]
Interest rate	4.63%
Parent Company | Junior subordinated debt
Debt Instrument [Line Items]
Interest rate	6.07%
Borrowed funds	$ 206	205
Subsidiaries
Debt Instrument [Line Items]
Borrowed funds	42,341	41,936
Subsidiaries | Senior debt
Debt Instrument [Line Items]
Borrowed funds	$ 4,525	5,283
Subsidiaries | Senior debt | Minimum
Debt Instrument [Line Items]
Interest rate	2.50%
Subsidiaries | Senior debt | Maximum
Debt Instrument [Line Items]
Interest rate	5.88%
Subsidiaries | Subordinated debt
Debt Instrument [Line Items]
Borrowed funds	$ 3,816	4,578
Subsidiaries | Subordinated debt | Minimum
Debt Instrument [Line Items]
Interest rate	2.70%
Subsidiaries | Subordinated debt | Maximum
Debt Instrument [Line Items]
Interest rate	5.90%
Subsidiaries | FHLB
Debt Instrument [Line Items]
Borrowed funds	$ 34,000	$ 32,075
Subsidiaries | FHLB | Minimum
Debt Instrument [Line Items]
Interest rate	5.25%
Subsidiaries | FHLB | Maximum
Debt Instrument [Line Items]
Interest rate	5.48%