Accumulated Other Comprehensive Income/(Loss) - Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 344,758
Net change	$ 1,365	$ 4,554	6,578	$ 3,659
Ending balance	360,212	345,836	360,212	345,836
Accumulated other comprehensive income/(loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(7,243)	(11,338)	(12,456)	(10,443)
Net change	1,365	4,554	6,578	3,659
Ending balance	(5,878)	(6,784)	(5,878)	(6,784)
Unrealized gains/(losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(3,065)	(3,494)	(3,830)	(3,743)
Net change	1,509	2,297	2,274	2,546
Ending balance	(1,556)	(1,197)	(1,556)	(1,197)
After-tax unamortized unrealized losses related to AFS securities transferred to HTM			(189)	(661)
Translation adjustments, net of hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(717)	(1,576)	(2,074)	(1,216)
Net change	(12)	389	1,345	29
Ending balance	(729)	(1,187)	(729)	(1,187)
Fair value hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(201)	(147)	(221)	(134)
Net change	37	(20)	57	(33)
Ending balance	(164)	(167)	(164)	(167)
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,611)	(4,843)	(4,814)	(3,932)
Net change	314	2,265	3,517	1,354
Ending balance	(1,297)	(2,578)	(1,297)	(2,578)
Defined benefit pension and OPEB plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,185)	(1,055)	(1,141)	(1,078)
Net change	4	(28)	(40)	(5)
Ending balance	(1,181)	(1,083)	(1,181)	(1,083)
DVA on fair value option elected liabilities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(464)	(223)	(376)	(340)
Net change	(487)	(349)	(575)	(232)
Ending balance	$ (951)	$ (572)	$ (951)	$ (572)