Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period			$ 28,887
Other comprehensive income (loss), net of taxes	$ (2,553)	$ 478	(6,348)	$ (733)
Balance, end of period	22,874	29,156	22,874	29,156
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	(3,210)	599	(8,027)	(946)
Income tax expense (benefit)	(657)	121	(1,679)	(213)
Other comprehensive income (loss), net of taxes	(2,553)	478	(6,348)	(733)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(2,602)	1,291	1,193	2,502
Other comprehensive income (loss) before reclassifications	(2,577)		(6,379)
Amounts reclassified from accumulated other comprehensive income, net of tax	24		31
Other comprehensive income (loss), net of taxes	(2,553)	478	(6,348)	(733)
Balance, end of period	(5,155)	1,769	(5,155)	1,769
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	(3,210)	599	(8,027)	(946)
Income tax expense (benefit)	(657)	121	(1,679)	(213)
Other comprehensive income (loss), net of taxes	(2,553)	478	(6,348)	(733)
Changes in Net Unrealized Gains (Losses) on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(1,572)		2,233
Other comprehensive income (loss) before reclassifications	(2,415)		(6,219)
Amounts reclassified from accumulated other comprehensive income, net of tax	16		15
Other comprehensive income (loss), net of taxes	(2,399)	422	(6,204)	(835)
Balance, end of period	(3,971)		(3,971)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	(3,045)	533	(7,874)	(1,063)
Income tax expense (benefit)	(646)	111	(1,670)	(228)
Other comprehensive income (loss), net of taxes	(2,399)	422	(6,204)	(835)
Changes in Net Unrealized Gains (Losses) on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	181		182
Other comprehensive income (loss) before reclassifications	(2)		(3)
Amounts reclassified from accumulated other comprehensive income, net of tax	0		0
Other comprehensive income (loss), net of taxes	(2)	0	(3)	0
Balance, end of period	179		179
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	(2)	0	(3)	0
Income tax expense (benefit)	0	0	0	0
Other comprehensive income (loss), net of taxes	(2)	0	(3)	0
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(464)		(473)
Other comprehensive income (loss) before reclassifications	1		2
Amounts reclassified from accumulated other comprehensive income, net of tax	8		16
Other comprehensive income (loss), net of taxes	9	20	18	40
Balance, end of period	(455)		(455)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	11	26	22	51
Income tax expense (benefit)	2	6	4	11
Other comprehensive income (loss), net of taxes	9	20	18	40
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(747)		(749)
Other comprehensive income (loss) before reclassifications	(161)		(159)
Amounts reclassified from accumulated other comprehensive income, net of tax	0		0
Other comprehensive income (loss), net of taxes	(161)	36	(159)	62
Balance, end of period	(908)		(908)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	(174)	40	(172)	66
Income tax expense (benefit)	(13)	4	(13)	4
Other comprehensive income (loss), net of taxes	$ (161)	$ 36	$ (159)	$ 62