Derivatives, Notional or Contractual Amounts and Fair Values of Derivatives (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022		Dec. 31, 2020
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Fair value derivative assets, gross	$ 85,596	$ 78,938
Fair value derivative assets, netting	(64,500)	(56,164)
Derivative assets	21,096	22,774
Fair value of derivative liabilities, gross	88,594	81,894
Fair value derivative liabilities, netting	(65,131)	(61,827)
Derivative liabilities	23,463	20,067	[1]	$ 16,482
Designated as hedging instrument [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Fair value derivative assets, gross	386	840
Fair value of derivative liabilities, gross	1,402	1,619
Designated as hedging instrument [Member] | Interest rate contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	347,039	263,876
Fair value derivative assets, gross	300	670
Fair value of derivative liabilities, gross	898	579
Designated as hedging instrument [Member] | Commodity contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	2,490	1,681
Fair value derivative assets, gross	29	9
Fair value of derivative liabilities, gross	4	25
Designated as hedging instrument [Member] | Foreign exchange contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	4,832	15,544
Fair value derivative assets, gross	57	161
Fair value of derivative liabilities, gross	500	1,015
Not designated as hedging instrument [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Fair value derivative assets, gross	85,210	78,098
Fair value of derivative liabilities, gross	87,192	80,275
Economic hedges [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Fair value derivative assets, gross	886	914
Fair value of derivative liabilities, gross	768	1,463
Economic hedges [Member] | Interest rate contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	58,689	65,727
Fair value derivative assets, gross	470	410
Fair value of derivative liabilities, gross	264	253
Economic hedges [Member] | Equity contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	4,666	3,326
Fair value derivative assets, gross	0	0
Fair value of derivative liabilities, gross	226	242
Economic hedges [Member] | Foreign exchange contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	28,409	38,139
Fair value derivative assets, gross	394	490
Fair value of derivative liabilities, gross	278	968
Economic hedges [Member] | Credit contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	490	290
Fair value derivative assets, gross	22	14
Fair value of derivative liabilities, gross	0	0
Customer accommodation trading and other derivatives [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Fair value derivative assets, gross	84,324	77,184
Fair value of derivative liabilities, gross	86,424	78,812
Customer accommodation trading and other derivatives [Member] | Interest rate contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	11,359,609	10,156,300
Fair value derivative assets, gross	43,037	40,006
Fair value of derivative liabilities, gross	49,687	42,641
Customer accommodation trading and other derivatives [Member] | Commodity contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	88,412	96,001
Fair value derivative assets, gross	3,913	5,991
Fair value of derivative liabilities, gross	2,101	3,420
Customer accommodation trading and other derivatives [Member] | Equity contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	450,904	390,427
Fair value derivative assets, gross	13,613	9,573
Fair value of derivative liabilities, gross	10,633	8,012
Customer accommodation trading and other derivatives [Member] | Foreign exchange contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	1,963,228	1,475,224
Fair value derivative assets, gross	23,705	21,562
Fair value of derivative liabilities, gross	23,978	24,703
Customer accommodation trading and other derivatives [Member] | Credit contracts [Member]
Notional Or Contractual Amounts And Fair Values For Derivatives [Abstract]
Notional or contractual amount	61,196	45,359
Fair value derivative assets, gross	56	52
Fair value of derivative liabilities, gross	$ 25	$ 36

[1] In first quarter 2023, we adopted ASU 2018-12 – Financial Services – Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts. For additional information, see Note 1 (Summary of Significant Accounting Policies).