Loans and ACL - 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
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses	$ 172	$ 135	$ 327	$ 285
Commercial \| Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	548	522	546	522
Charge-Offs	(22)	(23)	(39)	(46)
Recoveries	8	11	14	19
Provision for credit losses	40	25	53	40
ACL, ending balance	574	535	574	535
Commercial \| CRE
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	196	175	190	160
Charge-Offs	(18)	(2)	(26)	(8)
Recoveries	3	1	4	3
Provision for credit losses	20	17	33	36
ACL, ending balance	201	191	201	191
Commercial \| Lease financing
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	11	10	11	9
Charge-Offs	0	(1)	(1)	(2)
Recoveries	0	1	0	1
Provision for credit losses	(1)	0	0	2
ACL, ending balance	10	10	10	10
Retail \| Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	225	216	232	209
Charge-Offs	(5)	(5)	(10)	(9)
Recoveries	0	1	1	1
Provision for credit losses	4	9	1	20
ACL, ending balance	224	221	224	221
Retail \| Direct
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	96	99	97	106
Charge-Offs	(22)	(17)	(40)	(36)
Recoveries	7	6	13	12
Provision for credit losses	18	9	29	15
ACL, ending balance	99	97	99	97
Retail \| Indirect
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	358	347	356	348
Charge-Offs	(91)	(82)	(200)	(189)
Recoveries	19	17	36	32
Provision for credit losses	73	71	167	162
ACL, ending balance	359	353	359	353
Revolving credit
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	119	104	117	108
Charge-Offs	(25)	(21)	(51)	(42)
Recoveries	4	5	10	10
Provision for credit losses	22	17	44	29
ACL, ending balance	120	105	120	105
PCI
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	8	25	9	28
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	0	(7)	(1)	(10)
ACL, ending balance	8	18	8	18
ALLL
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	1,561	1,498	1,558	1,490
Charge-Offs	(183)	(151)	(367)	(332)
Recoveries	41	42	78	78
Provision for credit losses	176	141	326	294
ACL, ending balance	1,595	1,530	1,595	1,530
RUFC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	98	116	93	119
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	(4)	(6)	1	(9)
ACL, ending balance	94	110	94	110
ACL
Financing Receivable, Allowance for Credit Loss [Roll Forward]
ACL, beginning balance	1,659	1,614	1,651	1,609
Charge-Offs	(183)	(151)	(367)	(332)
Recoveries	41	42	78	78
Provision for credit losses	172	135	327	285
ACL, ending balance	$ 1,689	$ 1,640	$ 1,689	$ 1,640

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

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- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

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