Asset Quality - Allowance for Loan and Lease Losses and Corresponding Loan Balances (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Purchase Credit Impairment, Outstanding	$ 783	$ 865
Individually Evaluated for Impairment, Allowance, Total ALLL - Including Discontinued Operations	26	39
Collectively Evaluated for Impairment, Allowance, Total ALLL - Including Discontinued Operations	864	838
Purchased Credit Impaired, Allowance, Total ALLL - Including Discontinued Operations	8	5
Loans, Outstanding, Total ALLL - Including Discontinued Operations	87,864	87,603
Individually Evaluated for Impairment, Outstanding, Total ALLL - Including Discontinued Operations	402	523
Collectively Evaluated for Impairment, Outstanding, Total ALLL - Including Discontinued Operations	86,679	86,215
Purchased Credit Impaired, Outstanding, Total ALLL - Including Discontinued Operations	783	865
Loans at fair value	2
Continuing Operations [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	22	37
Collectively Evaluated for Impairment, Allowance	850	816
Purchase Credit Impairment, Allowance	8	5
Total loans	86,492	86,038
Individually Evaluated for Impairment, Outstanding	376	501
Collectively Evaluated for Impairment, Outstanding	85,333	84,672
Purchase Credit Impairment, Outstanding	783	865
Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Purchase Credit Impairment, Allowance	6	5
Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		24,129
Discontinued Operations [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	4	2
Collectively Evaluated for Impairment, Allowance	14	22
Purchase Credit Impairment, Allowance	0	0
Total loans	1,372	1,565
Individually Evaluated for Impairment, Outstanding	26	22
Collectively Evaluated for Impairment, Outstanding	1,346	1,543
Purchase Credit Impairment, Outstanding	0	0
Loans at fair value	2	3
Commercial and Industrial [Member] \| Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	7	17
Collectively Evaluated for Impairment, Allowance	522	486
Purchase Credit Impairment, Allowance	3	5
Total loans	41,147	39,768
Individually Evaluated for Impairment, Outstanding	157	284
Collectively Evaluated for Impairment, Outstanding	40,897	39,372
Purchase Credit Impairment, Outstanding	93	112
Commercial Real Estate: Commercial Mortgage [Member] \| Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	135	144
Purchase Credit Impairment, Allowance	3	0
Total loans	14,929	15,111
Individually Evaluated for Impairment, Outstanding	12	5
Collectively Evaluated for Impairment, Outstanding	14,641	14,784
Purchase Credit Impairment, Outstanding	275	322
Commercial Real Estate: Construction [Member] \| Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	29	22
Purchase Credit Impairment, Allowance	0	0
Total loans	1,954	2,345
Individually Evaluated for Impairment, Outstanding	0	0
Collectively Evaluated for Impairment, Outstanding	1,930	2,319
Purchase Credit Impairment, Outstanding	24	26
Commercial Real Estate Loans [Member] \| Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	164	166
Purchase Credit Impairment, Allowance	3	0
Total loans	16,883	17,456
Individually Evaluated for Impairment, Outstanding	12	5
Collectively Evaluated for Impairment, Outstanding	16,571	17,103
Purchase Credit Impairment, Outstanding	299	348
Commercial Lease Financing [Member] \| Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	43	42
Purchase Credit Impairment, Allowance	0	0
Total loans	4,716	4,685
Individually Evaluated for Impairment, Outstanding	0	0
Collectively Evaluated for Impairment, Outstanding	4,716	4,685
Purchase Credit Impairment, Outstanding	0	0
Commercial Loans [Member] \| Continuing Operations [Member] \| Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	7	17
Collectively Evaluated for Impairment, Allowance	729	694
Total loans	62,746	61,909
Individually Evaluated for Impairment, Outstanding	169	289
Collectively Evaluated for Impairment, Outstanding	62,184	61,160
Purchase Credit Impairment, Outstanding	392	460
Real Estate - Residential Mortgage [Member] \| Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	4	2
Collectively Evaluated for Impairment, Allowance	3	15
Purchase Credit Impairment, Allowance	1	0
Total loans	5,476	5,547
Individually Evaluated for Impairment, Outstanding	50	51
Collectively Evaluated for Impairment, Outstanding	5,064	5,128
Purchase Credit Impairment, Outstanding	362	368
Home Equity Loans [Member] \| Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	7	17
Collectively Evaluated for Impairment, Allowance	31	37
Purchase Credit Impairment, Allowance	1	0
Total loans	12,238	12,674
Individually Evaluated for Impairment, Outstanding	117	125
Collectively Evaluated for Impairment, Outstanding	12,098	12,519
Purchase Credit Impairment, Outstanding	24	30
Consumer Direct Loans [Member] \| Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	28	24
Purchase Credit Impairment, Allowance	0	0
Total loans	1,789	1,788
Individually Evaluated for Impairment, Outstanding	4	3
Collectively Evaluated for Impairment, Outstanding	1,780	1,778
Purchase Credit Impairment, Outstanding	5	7
Consumer Credit Card Financing Receivable [Member] \| Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	44	38
Purchase Credit Impairment, Allowance	0	0
Total loans	1,045	1,111
Individually Evaluated for Impairment, Outstanding	3	3
Collectively Evaluated for Impairment, Outstanding	1,042	1,108
Purchase Credit Impairment, Outstanding	0	0
Consumer Indirect Loans [Member] \| Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	4	1
Collectively Evaluated for Impairment, Allowance	15	8
Purchase Credit Impairment, Allowance	0	0
Total loans	3,198	3,009
Individually Evaluated for Impairment, Outstanding	33	30
Collectively Evaluated for Impairment, Outstanding	3,165	2,979
Purchase Credit Impairment, Outstanding	0	0
Consumer Loans [Member] \| Continuing Operations [Member] \| Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	15	20
Collectively Evaluated for Impairment, Allowance	121	122
Purchase Credit Impairment, Allowance	2	0
Total loans	23,746
Individually Evaluated for Impairment, Outstanding	207	212
Collectively Evaluated for Impairment, Outstanding	23,149	23,512
Purchase Credit Impairment, Outstanding	391	405
Education Lending [Member] \| Discontinued Operations [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans at fair value	$ 2	$ 3

Allowance for credit impairment.

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Financing receivable allowance for credit losses collectively evaluated for impairment total ALLL including discontinued operations.

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Financing receivable allowance for credit losses individually evaluated for impairment total ALLL including discontinued operations.

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Financing receivable collectively evaluated for impairment total all including discontinued operations.

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Financing receivable individually evaluated for impairment total all including discontinued operations.

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Loans total ALLL including discontinued operations.

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Loans and leases receivable, including loans at fair value net of deferred income.

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Purchased credit impaired loans allowance including discontinued operations.

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Purchased credit impaired loans outstanding including discontinued operations.

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Purchased credit impaired loans outstanding principal balance.

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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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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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

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

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

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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