Derivative Instruments and Hedging Activities - Hedged Items in Fair Value Hedging Relationship (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Hedged Items In Fair Value Hedging Relationship [Line Items]
Total Assets	$ 10	$ 33
Discontinued Hedging Relationships, Assets	1,900	2,200
Designated hedged items	1,300	1,500
Investment securities available for sale
Hedged Items In Fair Value Hedging Relationship [Line Items]
Carrying Amount Assets	6,022	6,108
Total Assets	(48)	(8)
Discontinued Hedging Relationships, Assets	109	126
Interest-bearing deposits
Hedged Items In Fair Value Hedging Relationship [Line Items]
Carrying Amount Liabilities	(16,991)	(17,374)
Total Liabilities	348	277
Discontinued Hedging Relationships, Liabilities	0	0
Securitized debt obligations
Hedged Items In Fair Value Hedging Relationship [Line Items]
Carrying Amount Liabilities	(13,358)	(13,375)
Total Liabilities	523	503
Discontinued Hedging Relationships, Liabilities	0	0
Senior and subordinated notes
Hedged Items In Fair Value Hedging Relationship [Line Items]
Carrying Amount Liabilities	(31,758)	(30,899)
Total Liabilities	1,325	971
Discontinued Hedging Relationships, Liabilities	$ (332)	$ (372)