Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale Without an Allowance for Credit Losses) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	$ (26)	$ (147)
Unrealized loss position less than 12 months	10,775	24,489
Unrealized loss position 12 months or more	(3,033)	(3,534)
Unrealized loss position 12 months or more	24,781	25,149
Total	(3,059)	(3,681)
Total	35,556	49,638
U.S. Treasury and government agencies
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(5)	(70)
Unrealized loss position less than 12 months	7,764	17,500
Unrealized loss position 12 months or more	(348)	(366)
Unrealized loss position 12 months or more	1,874	1,824
Total	(353)	(436)
Total	9,638	19,324
Residential mortgage-backed | Mortgage-backed Securities Agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(15)	(65)
Unrealized loss position less than 12 months	2,659	6,163
Unrealized loss position 12 months or more	(2,497)	(2,926)
Unrealized loss position 12 months or more	19,358	19,595
Total	(2,512)	(2,991)
Total	22,017	25,758
Residential mortgage-backed | Mortgage-backed Securities Non-agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	0	0
Unrealized loss position less than 12 months	0	0
Unrealized loss position 12 months or more	(2)	(3)
Unrealized loss position 12 months or more	33	41
Total	(2)	(3)
Total	33	41
Commercial mortgage servicing rights | Mortgage-backed Securities Agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(3)	(8)
Unrealized loss position less than 12 months	290	501
Unrealized loss position 12 months or more	(97)	(125)
Unrealized loss position 12 months or more	1,391	1,388
Total	(100)	(133)
Total	1,681	1,889
Commercial mortgage servicing rights | Mortgage-backed Securities Non-agency
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	0	0
Unrealized loss position less than 12 months	0	0
Unrealized loss position 12 months or more	(10)	(15)
Unrealized loss position 12 months or more	499	559
Total	(10)	(15)
Total	499	559
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	0	(2)
Unrealized loss position less than 12 months	0	226
Unrealized loss position 12 months or more	0	(1)
Unrealized loss position 12 months or more	0	8
Total	0	(3)
Total	0	234
Other
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position less than 12 months	(3)	(2)
Unrealized loss position less than 12 months	62	99
Unrealized loss position 12 months or more	(79)	(98)
Unrealized loss position 12 months or more	1,626	1,734
Total	(82)	(100)
Total	$ 1,688	$ 1,833