Derivatives, Gains (Losses) Recognized on Fair Value Hedging Relationships (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Line Items Presented in the Consolidated Statement of Income and Other Comprehensive Income [Abstract]
Debt securities	$ 2,563	$ 2,312
Deposits	(83)	(112)
Long-term debt	(761)	(1,026)
Other	556	982
Total recorded in OCI, Derivative gains (losses)	27	47
Derivatives (Textual) [Abstract]
Deferred net gains (losses) on derivatives in other comprehensive income	$ (17)
Maximum length of time hedged in cash flow hedge	10 years
Fair value hedging [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Recognized on derivatives, Total recorded in OCI	$ 64	25
Fair value hedging [Member] | Interest contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Recognized on derivatives, Total recorded in OCI	0	0
Fair value hedging [Member] | Foreign exchange contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Recognized on derivatives, Total recorded in OCI	64	25
Fair value hedging [Member] | Debt securities [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Total gains (losses) (pre-tax) on interest rate contracts	(27)	(3)
Fair value hedging [Member] | Debt securities [Member] | Interest contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	(41)	(67)
Recognized on derivatives	1,262	1,294
Recognized on hedged items	(1,248)	(1,258)
Total gains (losses) (pre-tax) on interest rate contracts	(27)	(31)
Fair value hedging [Member] | Debt securities [Member] | Foreign exchange contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	0	28
Recognized on derivatives	0	1
Recognized on hedged items	0	(1)
Total gains (losses) (pre-tax) on interest rate contracts	0	28
Fair value hedging [Member] | Deposits [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Total gains (losses) (pre-tax) on interest rate contracts	39	87
Fair value hedging [Member] | Deposits [Member] | Interest contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	41	91
Recognized on derivatives	(145)	(123)
Recognized on hedged items	143	119
Total gains (losses) (pre-tax) on interest rate contracts	39	87
Fair value hedging [Member] | Deposits [Member] | Foreign exchange contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	0	0
Recognized on derivatives	0	0
Recognized on hedged items	0	0
Total gains (losses) (pre-tax) on interest rate contracts	0	0
Fair value hedging [Member] | Long-term debt [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Total gains (losses) (pre-tax) on interest rate contracts	418	389
Fair value hedging [Member] | Long-term debt [Member] | Interest contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	481	550
Recognized on derivatives	(6,869)	(7,071)
Recognized on hedged items	6,813	6,944
Total gains (losses) (pre-tax) on interest rate contracts	425	423
Fair value hedging [Member] | Long-term debt [Member] | Foreign exchange contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	4	(1)
Recognized on derivatives	(456)	(227)
Recognized on hedged items	445	194
Total gains (losses) (pre-tax) on interest rate contracts	(7)	(34)
Fair value hedging [Member] | Other noninterest income [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Total gains (losses) (pre-tax) on interest rate contracts	(1)	(10)
Fair value hedging [Member] | Other noninterest income [Member] | Interest contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	0	0
Recognized on derivatives	0	0
Recognized on hedged items	0	0
Total gains (losses) (pre-tax) on interest rate contracts	0	0
Fair value hedging [Member] | Other noninterest income [Member] | Foreign exchange contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	0	0
Recognized on derivatives	(242)	307
Recognized on hedged items	241	(317)
Total gains (losses) (pre-tax) on interest rate contracts	(1)	(10)
Fair value hedging [Member] | Derivative gains (losses) [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Total gains (losses) (pre-tax) on interest rate contracts	429	463
Fair value hedging [Member] | Derivative gains (losses) [Member] | Interest contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	481	574
Recognized on derivatives	(5,752)	(5,900)
Recognized on hedged items	5,708	5,805
Total gains (losses) (pre-tax) on interest rate contracts	437	479
Fair value hedging [Member] | Derivative gains (losses) [Member] | Foreign exchange contracts [Member]
Total gains (losses) (pre-tax) recognized on fair value hedges
Amounts related to interest settlements on derivatives	4	27
Recognized on derivatives	(698)	81
Recognized on hedged items	686	(124)
Total gains (losses) (pre-tax) on interest rate contracts	$ (8)	$ (16)