Investment Securities - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value (Details) - USD ($) $ in Millions		Jun. 30, 2025	Dec. 31, 2024
AFS securities:
Amortized Cost		$ 71,652	$ 73,833
Gross Unrealized Gains		250	174
Gross Unrealized Losses		(5,512)	(6,543)
Net unrealized gains (losses)		(5,262)	(6,369)
AFS securities, Fair Value		66,390	67,464
Portfolio level basis adjustments(1)	[1]	89	(385)
Reversal of Hedged Asset	[1]	(89)	385
AFS securities Including Portfolio Level Basis Adjustments		71,741	73,448
AFS Securities, Accumulated Gross Unrealized Gain (Loss)		(5,351)	(5,984)
HTM securities:
Amortized Cost		48,973	50,640
HTM securities, Fair Value		39,611	40,286
U.S. Treasury
AFS securities:
Amortized Cost		13,389	14,279
Gross Unrealized Gains		114	156
Gross Unrealized Losses		(32)	(24)
Net unrealized gains (losses)		82	132
AFS securities, Fair Value		13,471	14,411
GSE
AFS securities:
Amortized Cost		459	441
Gross Unrealized Gains		3	1
Gross Unrealized Losses		(27)	(39)
Net unrealized gains (losses)		(24)	(38)
AFS securities, Fair Value		435	403
Agency MBS – residential
AFS securities:
Amortized Cost		54,173	55,769
Gross Unrealized Gains		116	6
Gross Unrealized Losses		(4,834)	(5,816)
Net unrealized gains (losses)		(4,718)	(5,810)
AFS securities, Fair Value		49,455	49,959
HTM securities:
Amortized Cost		48,973	50,640
Gross Unrealized Gains		0	0
Gross Unrealized Losses		(9,362)	(10,354)
HTM securities Unrealized Gains (Losses)		(9,362)	(10,354)
HTM securities, Fair Value		39,611	40,286
Agency MBS – commercial
AFS securities:
Amortized Cost		3,247	2,938
Gross Unrealized Gains		6	0
Gross Unrealized Losses		(600)	(645)
Net unrealized gains (losses)		(594)	(645)
AFS securities, Fair Value		2,653	2,293
States and political subdivisions
AFS securities:
Amortized Cost		369	390
Gross Unrealized Gains		11	11
Gross Unrealized Losses		(19)	(19)
Net unrealized gains (losses)		(8)	(8)
AFS securities, Fair Value		361	382
Other
AFS securities:
Amortized Cost		15	16
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	0
Net unrealized gains (losses)		0	0
AFS securities, Fair Value		$ 15	$ 16

[1] Represents fair value hedge basis adjustments related to active portfolio layer method hedges, which are not allocated to individual securities. For additional information, refer to “Note 16. Derivative Financial Instruments.”