Other Comprehensive Income (Loss) and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	$ 21,560
Other comprehensive income (loss), net of taxes	1,059	$ (3,795)
Balance, end of period	23,052	25,531
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	1,342	(4,817)
Income tax expense (benefit)	283	(1,022)
Other comprehensive income (loss), net of taxes	1,059	(3,795)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(6,445)	1,193
Other comprehensive income (loss) before reclassifications	1,053
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	6
Other comprehensive income (loss), net of taxes	1,059	(3,795)
Balance, end of period	(5,386)	(2,602)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	1,342	(4,817)
Income tax expense (benefit)	283	(1,022)
Other comprehensive income (loss), net of taxes	1,059	(3,795)
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	(5,077)
Other comprehensive income (loss) before reclassifications	1,021
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	9
Other comprehensive income (loss), net of taxes	1,030	(3,805)
Balance, end of period	(4,047)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	1,308	(4,829)
Income tax expense (benefit)	278	(1,024)
Other comprehensive income (loss), net of taxes	1,030	(3,805)
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	179
Other comprehensive income (loss) before reclassifications
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0
Other comprehensive income (loss), net of taxes	0	(1)
Balance, end of period	179
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	0	(1)
Income tax expense (benefit)	0	0
Other comprehensive income (loss), net of taxes	0	(1)
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(542)
Other comprehensive income (loss) before reclassifications	1
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(3)
Other comprehensive income (loss), net of taxes	(2)	9
Balance, end of period	(544)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	(3)	11
Income tax expense (benefit)	(1)	2
Other comprehensive income (loss), net of taxes	(2)	9
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Balance, beginning of period	(1,005)
Other comprehensive income (loss) before reclassifications	31
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0
Other comprehensive income (loss), net of taxes	31	2
Balance, end of period	(974)
Pre-tax components of other comprehensive income (loss) and the related income tax expense (benefit)
Other comprehensive income (loss), before taxes	37	2
Income tax expense (benefit)	6	0
Other comprehensive income (loss), net of taxes	$ 31	$ 2