Derivatives (Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets) (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value
Fair value - Derivative Assets	$ 1,177	$ 1,114
Fair value - Derivative Liabilities	880	874
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Fair value - Derivative Assets	399	346
Fair value - Derivative Liabilities	51	29
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	308	262
Fair value - Derivative Liabilities	3	2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging \| Interest Rate Swap \| Long-Term Debt
Derivatives, Fair Value
Derivative, Notional Amount	3,455	3,455
Fair value - Derivative Assets	308	262
Fair value - Derivative Liabilities	3	2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	91	84
Fair value - Derivative Liabilities	48	27
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Swap \| Commercial and Industrial Loans
Derivatives, Fair Value
Derivative, Notional Amount	8,000	8,000
Fair value - Derivative Assets	20	15
Fair value - Derivative Liabilities	48	27
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Floor \| Commercial and Industrial Loans
Derivatives, Fair Value
Derivative, Notional Amount	3,000	3,000
Fair value - Derivative Assets	71	69
Fair value - Derivative Liabilities	0	0
Nondesignated
Derivatives, Fair Value
Fair value - Derivative Assets	778	768
Fair value - Derivative Liabilities	829	845
Nondesignated \| Forward Contracts \| FHLB advance
Derivatives, Fair Value
Derivative, Notional Amount	4
Fair value - Derivative Assets	0
Fair value - Derivative Liabilities	0
Nondesignated \| Risk Management And Other Business Purposes
Derivatives, Fair Value
Fair value - Derivative Assets	82	44
Fair value - Derivative Liabilities	166	147
Nondesignated \| Risk Management And Other Business Purposes \| Interest Rate Contract \| Servicing Contracts
Derivatives, Fair Value
Derivative, Notional Amount	11,755	10,045
Fair value - Derivative Assets	81	40
Fair value - Derivative Liabilities	15	14
Nondesignated \| Risk Management And Other Business Purposes \| Forward Contracts \| Loans Held For Sale
Derivatives, Fair Value
Derivative, Notional Amount	1,009	926
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	8	8
Nondesignated \| Risk Management And Other Business Purposes \| Swap
Derivatives, Fair Value
Derivative, Notional Amount	2,573	2,174
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	143	125
Nondesignated \| Risk Management And Other Business Purposes \| Foreign Exchange Contract
Derivatives, Fair Value
Derivative, Notional Amount	167	133
Fair value - Derivative Assets	1	4
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation
Derivatives, Fair Value
Fair value - Derivative Assets	696	724
Fair value - Derivative Liabilities	663	698
Nondesignated \| Customer Accommodation \| Interest Rate Contract
Derivatives, Fair Value
Derivative, Notional Amount	63,445	55,012
Fair value - Derivative Assets	357	262
Fair value - Derivative Liabilities	367	278
Nondesignated \| Customer Accommodation \| Interest Rate Lock Commitments
Derivatives, Fair Value
Derivative, Notional Amount	555	407
Fair value - Derivative Assets	11	7
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation \| Commodity Contract
Derivatives, Fair Value
Derivative, Notional Amount	6,862	6,511
Fair value - Derivative Assets	190	307
Fair value - Derivative Liabilities	170	278
Nondesignated \| Customer Accommodation \| TBAs
Derivatives, Fair Value
Derivative, Notional Amount	24	18
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation \| Foreign Exchange Contract
Derivatives, Fair Value
Derivative, Notional Amount	14,069	13,205
Fair value - Derivative Assets	138	148
Fair value - Derivative Liabilities	$ 126	$ 142

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=SL51823488-111719

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
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-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=SL51823488-111719

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-Subparagraph (a),(c)
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

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- Definition

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.

+ References

No definition available.

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