Accumulated Other Comprehensive Income/(Loss) - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 327,878	$ 292,332
Net change	(2,013)	6,898	$ (17,257)
Ending balance	344,758	327,878	292,332
Accumulated other comprehensive income/(loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(10,443)	(17,341)	(84)
Net change	(2,013)	6,898	(17,257)
Ending balance	(12,456)	(10,443)	(17,341)
Unrealized gains/(losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(3,743)	(9,124)	2,640
Net change	(87)	5,381	(11,764)
Ending balance	(3,830)	(3,743)	(9,124)
After-tax unamortized unrealized gains/(losses) related to transfer of AFS securities to HTM	(651)	(895)	(1,300)
After-tax unrealized gains/ (losses) related to HTM securities that have been transferred to AFS		(29)
Translation adjustments, net of hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,216)	(1,545)	(934)
Net change	(858)	329	(611)
Ending balance	(2,074)	(1,216)	(1,545)
Fair value hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(134)	(33)	(131)
Net change	(87)	(101)	98
Ending balance	(221)	(134)	(33)
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(3,932)	(5,656)	(296)
Net change	(882)	1,724	(5,360)
Ending balance	(4,814)	(3,932)	(5,656)
Defined benefit pension and OPEB plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,078)	(1,451)	(210)
Net change	(63)	373	(1,241)
Ending balance	(1,141)	(1,078)	(1,451)
DVA on fair value option elected liabilities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(340)	468	(1,153)
Net change	(36)	(808)	1,621
Ending balance	$ (376)	$ (340)	$ 468