Loans and Allowance for Credit Losses, Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance	$ 10,821	$ 11,313	$ 10,707	$ 11,960
Provision for credit losses	503	452	1,348	643
Interest income on certain impaired loans	(39)	(43)	(78)	(86)
Loan charge-offs	(1,033)	(1,059)	(2,096)	(2,215)
Loan recoveries	380	457	748	872
Net loan charge-offs	(653)	(602)	(1,348)	(1,343)
Other	(29)	(10)	(26)	(64)
Allowance for credit losses, ending balance	10,603	11,110	10,603	11,110
Components:
Allowance for loan losses					$ 9,692	$ 9,775
Total allowance for credit losses	$ 10,603	$ 11,110	$ 10,603	$ 11,960	$ 10,603	10,707	$ 11,110
Net loan charge-offs (annualized) as a percentage of average total loans	0.28%	0.26%	0.29%	0.29%
Allowance for loan losses as a percentage of total loans					1.02%		1.08%
Allowance for credit losses as a percentage of total loans					1.12%		1.18%
SEC Schedule, 12-09, Allowance, Loss on Finance Receivable [Member]
Components:
Allowance for loan losses					$ 9,692		$ 10,193
SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member]
Components:
Allowance for loan losses					911		917
Total Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance	$ 6,428	$ 6,708	$ 6,417	$ 6,632
Provision for credit losses	46	89	210	258
Interest income on certain impaired loans	(14)	(14)	(25)	(25)
Loan charge-offs	(231)	(173)	(431)	(356)
Loan recoveries	66	106	121	211
Net loan charge-offs	(165)	(67)	(310)	(145)
Other	3	(5)	6	(9)
Allowance for credit losses, ending balance	6,298	6,711	6,298	6,711
Components:
Total allowance for credit losses	6,428	6,708	6,298	6,632	6,298	6,417	6,711
Commercial and industrial loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(205)	(134)	(381)	(298)
Loan recoveries	46	76	89	155
Commercial real estate mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(14)	(19)	(26)	(21)
Loan recoveries	10	19	16	36
Commercial real estate construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	0	0	(1)	0
Loan recoveries	2	6	5	10
Commercial lease financing receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(12)	(20)	(23)	(37)
Loan recoveries	8	5	11	10
Total Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning balance	4,393	4,605	4,290	5,328
Provision for credit losses	457	363	1,138	385
Interest income on certain impaired loans	(25)	(29)	(53)	(61)
Loan charge-offs	(802)	(886)	(1,665)	(1,859)
Loan recoveries	314	351	627	661
Net loan charge-offs	(488)	(535)	(1,038)	(1,198)
Other	(32)	(5)	(32)	(55)
Allowance for credit losses, ending balance	4,305	4,399	4,305	4,399
Components:
Total allowance for credit losses	4,393	4,605	4,290	4,399	$ 4,305	$ 4,290	$ 4,399
Real estate 1-4 family first mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(27)	(55)	(70)	(96)
Loan recoveries	57	78	112	137
Real estate 1-4 family junior lien mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(29)	(47)	(63)	(94)
Loan recoveries	48	60	91	115
Credit Card [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(437)	(404)	(874)	(809)
Loan recoveries	88	81	173	154
Automobile [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(142)	(216)	(329)	(516)
Loan recoveries	90	103	186	195
Other revolving credit and installment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loan charge-offs	(167)	(164)	(329)	(344)
Loan recoveries	$ 31	$ 29	$ 65	$ 60