Accumulated Other Comprehensive Income/(Loss) - Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 294,127
Net change	(9,483)	$ (6,945)
Ending balance	285,899	280,714
Accumulated other comprehensive income/(loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(84)	7,986
Net change	(9,483)	(6,945)
Ending balance	(9,567)	1,041
Unrealized gains/(losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	2,640	8,180
Net change	(7,453)	(4,339)
Ending balance	(4,813)	3,841
After-tax unamortized unrealized gains related to transfer of AFS securities to HTM	2,200	2,900
Translation adjustments, net of hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(934)	(473)
Net change	(62)	(250)
Ending balance	(996)	(723)
Fair value hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(131)	(112)
Net change	110	(28)
Ending balance	(21)	(140)
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(296)	2,383
Net change	(2,791)	(2,249)
Ending balance	(3,087)	134
Defined benefit pension and OPEB plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(210)	(1,132)
Net change	67	68
Ending balance	(143)	(1,064)
DVA on fair value option elected liabilities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,153)	(860)
Net change	646	(147)
Ending balance	$ (507)	$ (1,007)