AFS and HTM Debt Securities, HTM Debt Securities Purchases and Transfers (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Held-to-maturity Purchase or Transfer of Investment [Abstract]
Purchases of held-to-maturity debt securities		$ 39	$ 39	$ 4,312	$ 3,092
Transfers from available-for-sale debt securities to held-to-maturity debt securities		0	5,550	3,687	48,591
AFS and HTM Debt Securities Textual [Abstract]
Unrealized losses on debt securities transferred from AFS to HTM, before Tax		0	456	320	4,300
Securities of U.S. states and political subdivisions [Member]
Debt Securities, Held-to-maturity Purchase or Transfer of Investment [Abstract]
Purchases of held-to-maturity debt securities		0	0	0	843
Federal agency mortgage-backed securities [Member]
Debt Securities, Held-to-maturity Purchase or Transfer of Investment [Abstract]
Purchases of held-to-maturity debt securities		0	0	4,225	2,051
Transfers from available-for-sale debt securities to held-to-maturity debt securities		0	5,550	3,687	48,591
Non-agency mortgage-backed securities [Member]
Debt Securities, Held-to-maturity Purchase or Transfer of Investment [Abstract]
Purchases of held-to-maturity debt securities		$ 39	$ 39	$ 87	$ 198
Accounting Standards Update 2022-01 [Member] | Fixed rate securities [Member]
AFS and HTM Debt Securities Textual [Abstract]
Debt securities, available-for-sale, fair value, transfer from, held-to-maturity, amount	$ 23,200