Loans and Related Allowance for Credit Losses, Allowance for Credit Losses for Loans Activity by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period	$ 14,789	$ 14,786	$ 15,088	$ 13,609	$ 13,609
Provision for credit losses	1,059	1,143	3,214	4,111
Loan charge-offs, total	(1,379)	(1,117)	(4,354)	(3,065)
Loan recoveries, total	268	267	793	847
Net loan charge-offs	(1,111)	(850)	(3,561)	(2,218)
Other	2	(15)	(2)	(9)
Allowance for credit losses, end of period	14,739	15,064	14,739	15,064	15,088
Cumulative effect from change in accounting policies, period of adoption adjustment [Member] | Accounting Standards Update 2022-02 [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period	0	0	0	(429)	(429)
Allowance for credit losses, end of period					0
Cumulative effect from change in accounting policies, period of adoption adjusted balance [Member] | Accounting Standards Update 2022-02 [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period	14,789	14,786	15,088	13,180	13,180
Allowance for credit losses, end of period					15,088
Total Commercial [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period	8,236	8,081	8,412	6,956	6,956
Provision for credit losses	178	433	815	1,793
Loan charge-offs, total	(363)	(230)	(1,259)	(599)
Loan recoveries, total	40	42	127	148
Net loan charge-offs	(323)	(188)	(1,132)	(451)
Other	1	(16)	(3)	(15)
Allowance for credit losses, end of period	8,092	8,310	8,092	8,310	8,412
Total Commercial [Member] | Cumulative effect from change in accounting policies, period of adoption adjustment [Member] | Accounting Standards Update 2022-02 [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period			0	27	27
Allowance for credit losses, end of period					0
Total Commercial [Member] | Cumulative effect from change in accounting policies, period of adoption adjusted balance [Member] | Accounting Standards Update 2022-02 [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period			8,412	6,983	6,983
Allowance for credit losses, end of period					8,412
Total Consumer [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period	6,553	6,705	6,676	6,653	6,653
Provision for credit losses	881	710	2,399	2,318
Loan charge-offs, loans	(1,016)	(887)	(3,095)	(2,466)
Loan recoveries, loans	228	225	666	699
Net loan charge-offs	(788)	(662)	(2,429)	(1,767)
Other	1	1	1	6
Allowance for credit losses, end of period	$ 6,647	$ 6,754	6,647	6,754	6,676
Total Consumer [Member] | Cumulative effect from change in accounting policies, period of adoption adjustment [Member] | Accounting Standards Update 2022-02 [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period			0	(456)	(456)
Allowance for credit losses, end of period					0
Total Consumer [Member] | Cumulative effect from change in accounting policies, period of adoption adjusted balance [Member] | Accounting Standards Update 2022-02 [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning of period			$ 6,676	$ 6,197	6,197
Allowance for credit losses, end of period					$ 6,676