Accumulated Other Comprehensive Income - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2023		Sep. 30, 2022	Sep. 30, 2023		Sep. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 37,147		$ 44,513	$ 36,608	[1]	$ 56,261
Other net changes	(22)		(7,130)	1,869		(22,043)
Balance at end of period	37,784	[1]	37,041	37,784	[1]	37,041
Accumulated other comprehensive income, tax expense (benefit)	(29)		(2,264)	508		(6,960)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(20,730)		(16,022)	(22,621)		(1,109)
Other net changes	(22)		(7,130)	1,869		(22,043)
Balance at end of period	(20,752)		(23,152)	(20,752)		(23,152)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other net changes	(538)		(7,207)	367		(22,272)
Accumulated other comprehensive income, tax expense (benefit)	(182)		(2,286)	79		(7,027)
Net Unrealized Gain (Loss) on Securities Transferred to Held-to-Maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other net changes						1,850
Accumulated other comprehensive income, tax expense (benefit)						579
Other Reclassifications Included in Other Revenue from Sale of Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other net changes	18		12	33		(1)
Accumulated other comprehensive income, tax expense (benefit)	6		4	11
Net Unrealized Gain (Loss) on Securities Transferred from Available-for-Sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other net changes						(1,850)
Accumulated other comprehensive income, tax expense (benefit)						579
Amortization of Held to Maturity Securities Transferred from Available for Sale Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other net changes	498		65	1,476		230
Accumulated other comprehensive income, tax expense (benefit)	$ 147		$ 18	420		67
Other Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other net changes				(7)
Accumulated other comprehensive income, tax expense (benefit)				$ (2)
Other Accumulated Other Comprehensive Income | Maximum
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, tax expense (benefit)						$ 1

[1] Certain prior year amounts have been reclassified to conform to the current year presentation. See Note 1 for additional information.