Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale Without an Allowance for Credit Losses) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	$ (147)	$ (8)
Unrealized loss position less than 12 months	24,489	1,108
Unrealized loss position 12 months or more	(3,534)	(3,792)
Unrealized loss position 12 months or more	25,149	34,766
Total	(3,681)	(3,800)
Total	49,638	35,874
U.S. Treasury and government agencies
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(70)
Unrealized loss position less than 12 months	17,500
Unrealized loss position 12 months or more	(366)	(666)
Unrealized loss position 12 months or more	1,824	6,035
Total	(436)	(666)
Total	19,324	6,035
Residential mortgage-backed Securities | Mortgage-backed Securities Agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(65)	(4)
Unrealized loss position less than 12 months	6,163	1,015
Unrealized loss position 12 months or more	(2,926)	(2,805)
Unrealized loss position 12 months or more	19,595	24,306
Total	(2,991)	(2,809)
Total	25,758	25,321
Residential mortgage-backed Securities | Mortgage-backed Securities Non-agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months		(1)
Unrealized loss position less than 12 months		15
Unrealized loss position 12 months or more	(3)	(4)
Unrealized loss position 12 months or more	41	84
Total	(3)	(5)
Total	41	99
Commercial Mortgage-Backed Securities | Mortgage-backed Securities Agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(8)
Unrealized loss position less than 12 months	501
Unrealized loss position 12 months or more	(125)	(135)
Unrealized loss position 12 months or more	1,388	1,495
Total	(133)	(135)
Total	1,889	1,495
Commercial Mortgage-Backed Securities | Mortgage-backed Securities Non-agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months
Unrealized loss position less than 12 months
Unrealized loss position 12 months or more	(15)	(45)
Unrealized loss position 12 months or more	559	731
Total	(15)	(45)
Total	559	731
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(2)
Unrealized loss position less than 12 months	226
Unrealized loss position 12 months or more	(1)	(1)
Unrealized loss position 12 months or more	8	9
Total	(3)	(1)
Total	234	9
Other debt
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(2)	(3)
Unrealized loss position less than 12 months	99	78
Unrealized loss position 12 months or more	(98)	(136)
Unrealized loss position 12 months or more	1,734	2,106
Total	(100)	(139)
Total	$ 1,833	$ 2,184