Accumulated Other Comprehensive Income/(Loss) - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 292,332	$ 294,127
Net change	6,898	(17,257)	$ (8,070)
Ending balance	327,878	292,332	294,127
Accumulated other comprehensive income/(loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(17,341)	(84)	7,986
Net change	6,898	(17,257)	(8,070)
Ending balance	(10,443)	(17,341)	(84)
Unrealized gains/(losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(9,124)	2,640	8,180
Net change	5,381	(11,764)	(5,540)
Ending balance	(3,743)	(9,124)	2,640
After-tax unrealized gains/ (losses) related to HTM securities that have been transferred to AFS	(29)
After-tax unamortized unrealized gains/(losses) related to transfer of AFS securities to HTM	(895)	(1,300)	2,400
Translation adjustments, net of hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,545)	(934)	(473)
Net change	329	(611)	(461)
Ending balance	(1,216)	(1,545)	(934)
Fair value hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(33)	(131)	(112)
Net change	(101)	98	(19)
Ending balance	(134)	(33)	(131)
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(5,656)	(296)	2,383
Net change	1,724	(5,360)	(2,679)
Ending balance	(3,932)	(5,656)	(296)
Defined benefit pension and OPEB plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,451)	(210)	(1,132)
Net change	373	(1,241)	922
Ending balance	(1,078)	(1,451)	(210)
DVA on fair value option elected liabilities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	468	(1,153)	(860)
Net change	(808)	1,621	(293)
Ending balance	$ (340)	$ 468	$ (1,153)