Borrowed Funds (FHLB Borrowings, Senior Debt and Subordinated Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Carrying value of debt	$ 82,956	$ 54,658
Parent Company
Debt Instrument [Line Items]
Carrying value of debt	37,649	33,664
Parent Company \| Senior debt
Debt Instrument [Line Items]
Carrying value of debt	$ 35,165	32,650
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]
Carrying value of debt	$ 2,278	808
Parent Company \| Subordinated debt \| Minimum
Debt Instrument [Line Items]
Interest rate	4.63%
Parent Company \| Subordinated debt \| Maximum
Debt Instrument [Line Items]
Interest rate	5.42%
Parent Company \| Junior subordinated debt
Debt Instrument [Line Items]
Interest rate	4.49%
Carrying value of debt	$ 206	206
Subsidiaries
Debt Instrument [Line Items]
Carrying value of debt	45,307	20,994
Subsidiaries \| Senior debt
Debt Instrument [Line Items]
Carrying value of debt	$ 2,979	5,992
Subsidiaries \| Senior debt \| Minimum
Debt Instrument [Line Items]
Interest rate	3.10%
Subsidiaries \| Senior debt \| Maximum
Debt Instrument [Line Items]
Interest rate	4.43%
Subsidiaries \| Subordinated debt
Debt Instrument [Line Items]
Carrying value of debt	$ 1,912	2,002
Subsidiaries \| Subordinated debt \| Minimum
Debt Instrument [Line Items]
Interest rate	2.70%
Subsidiaries \| Subordinated debt \| Maximum
Debt Instrument [Line Items]
Interest rate	4.05%
Subsidiaries \| FHLB
Debt Instrument [Line Items]
Carrying value of debt	$ 40,416	$ 13,000
Subsidiaries \| FHLB \| Minimum
Debt Instrument [Line Items]
Interest rate	3.25%
Subsidiaries \| FHLB \| Maximum
Debt Instrument [Line Items]
Interest rate	4.21%