Loans and ACL - Schedule of Loans Collectively Evaluated for Impairment (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable [Line Items]
Recorded Investment	$ 142,044	$ 141,395
Related ALLL	1,319	1,297
Commercial \| Commercial and industrial
Financing Receivable [Line Items]
Recorded Investment	58,804	57,265
Related ALLL	494	492
Commercial \| CRE
Financing Receivable [Line Items]
Recorded Investment	21,173	19,649
Related ALLL	154	136
Commercial \| Lease financing
Financing Receivable [Line Items]
Recorded Investment	1,910	1,672
Related ALLL	9	7
Retail \| Residential mortgage
Financing Receivable [Line Items]
Recorded Investment	27,914	28,954
Related ALLL	143	144
Retail \| Direct
Financing Receivable [Line Items]
Recorded Investment	11,815	12,011
Related ALLL	98	93
Retail \| Indirect
Financing Receivable [Line Items]
Recorded Investment	16,935	18,308
Related ALLL	296	286
Revolving credit
Financing Receivable [Line Items]
Recorded Investment	2,842	2,626
Related ALLL	97	95
PCI
Financing Receivable [Line Items]
Recorded Investment	651	910
Related ALLL	$ 28	$ 44

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No definition available.

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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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