Borrowed Funds (FHLB Borrowings, Senior Debt and Subordinated Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Carrying value of debt	$ 64,688	$ 69,711
Parent Company
Debt Instrument [Line Items]
Carrying value of debt	29,414	23,971
Parent Company | Senior debt
Debt Instrument [Line Items]
Carrying value of debt	$ 28,394	22,221
Parent Company | Senior debt | Minimum
Debt Instrument [Line Items]
Interest rate	1.15%
Parent Company | Senior debt | Maximum
Debt Instrument [Line Items]
Interest rate	6.88%
Parent Company | Subordinated debt
Debt Instrument [Line Items]
Interest rate	4.63%
Carrying value of debt	$ 814	1,544
Parent Company | Junior subordinated debt
Debt Instrument [Line Items]
Interest rate	5.85%
Carrying value of debt	$ 206	206
Subsidiaries
Debt Instrument [Line Items]
Carrying value of debt	35,274	45,740
Subsidiaries | Senior debt
Debt Instrument [Line Items]
Carrying value of debt	$ 4,098	4,615
Subsidiaries | Senior debt | Minimum
Debt Instrument [Line Items]
Interest rate	2.95%
Subsidiaries | Senior debt | Maximum
Debt Instrument [Line Items]
Interest rate	5.99%
Subsidiaries | Subordinated debt
Debt Instrument [Line Items]
Carrying value of debt	$ 3,176	3,125
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]
Carrying value of debt	$ 28,000	$ 38,000
Subsidiaries | FHLB | Minimum
Debt Instrument [Line Items]
Interest rate	5.07%
Subsidiaries | FHLB | Maximum
Debt Instrument [Line Items]
Interest rate	5.43%