Derivatives (Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets) (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value
Fair value - Derivative Assets	$ 1,114	$ 823
Fair value - Derivative Liabilities	874	602
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Fair value - Derivative Assets	346	297
Fair value - Derivative Liabilities	29	17
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	262	297
Fair value - Derivative Liabilities	2	5
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging \| Interest Rate Swap \| Long-Term Debt
Derivatives, Fair Value
Notional amount	3,455	3,705
Fair value - Derivative Assets	262	297
Fair value - Derivative Liabilities	2	5
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	84	0
Fair value - Derivative Liabilities	27	12
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Swap \| Commercial and Industrial Loans
Derivatives, Fair Value
Notional amount	8,000	4,475
Fair value - Derivative Assets	15	0
Fair value - Derivative Liabilities	27	12
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Floor \| Commercial and Industrial Loans
Derivatives, Fair Value
Notional amount	3,000
Fair value - Derivative Assets	69
Fair value - Derivative Liabilities	0
Nondesignated
Derivatives, Fair Value
Fair value - Derivative Assets	768	526
Fair value - Derivative Liabilities	845	585
Nondesignated \| Risk Management and Other Business Purposes
Derivatives, Fair Value
Fair value - Derivative Assets	44	75
Fair value - Derivative Liabilities	147	154
Nondesignated \| Risk Management and Other Business Purposes \| Interest Rate Contract \| Mortgage Servicing Rights
Derivatives, Fair Value
Notional amount	10,045	11,035
Fair value - Derivative Assets	40	54
Fair value - Derivative Liabilities	14	15
Nondesignated \| Risk Management and Other Business Purposes \| Forward Contracts \| Assets Held For Sale \| Residential Mortgage
Derivatives, Fair Value
Notional amount	926	1,284
Fair value - Derivative Assets	0	1
Fair value - Derivative Liabilities	8	1
Nondesignated \| Risk Management and Other Business Purposes \| Warrant
Derivatives, Fair Value
Notional amount		20
Fair value - Derivative Assets		20
Fair value - Derivative Liabilities		0
Nondesignated \| Risk Management and Other Business Purposes \| Swap
Derivatives, Fair Value
Notional amount	2,174	1,900
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	125	137
Nondesignated \| Risk Management and Other Business Purposes \| Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	133	112
Fair value - Derivative Assets	4	0
Fair value - Derivative Liabilities	0	1
Nondesignated \| Customer Accommodation
Derivatives, Fair Value
Fair value - Derivative Assets	724	451
Fair value - Derivative Liabilities	698	431
Nondesignated \| Customer Accommodation \| Interest Rate Contract
Derivatives, Fair Value
Notional amount	55,012	42,216
Fair value - Derivative Assets	262	154
Fair value - Derivative Liabilities	278	145
Nondesignated \| Customer Accommodation \| Interest Rate Lock Commitments
Derivatives, Fair Value
Notional amount	407	446
Fair value - Derivative Assets	7	8
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation \| Commodity Contract
Derivatives, Fair Value
Notional amount	6,511	4,125
Fair value - Derivative Assets	307	165
Fair value - Derivative Liabilities	278	167
Nondesignated \| Customer Accommodation \| TBA Securities
Derivatives, Fair Value
Notional amount	18	26
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation \| Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	13,205	12,654
Fair value - Derivative Assets	148	124
Fair value - Derivative Liabilities	$ 142	$ 119

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
-Subparagraph (a)
-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
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-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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