Borrowed Funds (FHLB Borrowings, Bank Notes, Senior Debt and Subordinated Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Carrying Value	$ 58,601	$ 69,711
Parent Company
Debt Instrument [Line Items]
Carrying Value	28,352	23,971
Bank
Debt Instrument [Line Items]
Carrying Value	30,249	45,740
Senior debt | Parent Company
Debt Instrument [Line Items]
Carrying Value	$ 27,369	22,221
Senior debt | Parent Company | Minimum
Debt Instrument [Line Items]
Stated interest rate	1.15%
Senior debt | Parent Company | Maximum
Debt Instrument [Line Items]
Stated interest rate	6.88%
Senior debt | Bank
Debt Instrument [Line Items]
Carrying Value	$ 5,128	4,615
Senior debt | Bank | Minimum
Debt Instrument [Line Items]
Stated interest rate	2.95%
Senior debt | Bank | Maximum
Debt Instrument [Line Items]
Stated interest rate	4.87%
Subordinated debt | Parent Company
Debt Instrument [Line Items]
Stated interest rate	4.63%
Carrying Value	$ 777	1,544
Subordinated debt | Bank
Debt Instrument [Line Items]
Carrying Value	$ 3,121	3,125
Subordinated debt | Bank | Minimum
Debt Instrument [Line Items]
Stated interest rate	2.70%
Subordinated debt | Bank | Maximum
Debt Instrument [Line Items]
Stated interest rate	5.90%
Junior subordinated debt | Parent Company
Debt Instrument [Line Items]
Stated interest rate	5.33%
Carrying Value	$ 206	206
Federal Home Loan Bank advances | Bank
Debt Instrument [Line Items]
Carrying Value	$ 22,000	$ 38,000
Federal Home Loan Bank advances | Bank | Minimum
Debt Instrument [Line Items]
Stated interest rate	4.63%
Federal Home Loan Bank advances | Bank | Maximum
Debt Instrument [Line Items]
Stated interest rate	4.96%