Derivatives - Derivative Instruments Included in the Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	$ 1,700	$ 1,114
Fair value - Derivative Liabilities	1,202	874
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	542	346
Fair value - Derivative Liabilities	31	29
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	388	262
Fair value - Derivative Liabilities	2	2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging \| Interest Rate Swap \| Long-Term Debt
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,455	3,455
Fair value - Derivative Assets	388	262
Fair value - Derivative Liabilities	2	2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	154	84
Fair value - Derivative Liabilities	29	27
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Swap \| Commercial and Industrial Loans
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	8,000	8,000
Fair value - Derivative Assets	30	15
Fair value - Derivative Liabilities	29	27
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Floor \| Commercial and Industrial Loans
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,000	3,000
Fair value - Derivative Assets	124	69
Fair value - Derivative Liabilities	0	0
Nondesignated
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	1,158	768
Fair value - Derivative Liabilities	1,171	845
Nondesignated \| Risk Management And Other Business Purposes
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	127	44
Fair value - Derivative Liabilities	179	147
Nondesignated \| Risk Management And Other Business Purposes \| Interest Rate Contract \| Servicing Contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	9,435	10,045
Fair value - Derivative Assets	127	40
Fair value - Derivative Liabilities	11	14
Nondesignated \| Risk Management And Other Business Purposes \| Forward Contracts \| Loans Held For Sale
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,541	926
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	13	8
Nondesignated \| Risk Management And Other Business Purposes \| Swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,859	2,174
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	151	125
Nondesignated \| Risk Management And Other Business Purposes \| Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	176	133
Fair value - Derivative Assets	0	4
Fair value - Derivative Liabilities	4	0
Nondesignated \| Customer Accommodation
Derivatives, Fair Value [Line Items]
Fair value - Derivative Assets	1,031	724
Fair value - Derivative Liabilities	992	698
Nondesignated \| Customer Accommodation \| Interest Rate Contract
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	66,529	55,012
Fair value - Derivative Assets	607	262
Fair value - Derivative Liabilities	600	278
Nondesignated \| Customer Accommodation \| Interest Rate Lock Commitments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	686	407
Fair value - Derivative Assets	14	7
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation \| Commodity Contract
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,802	6,511
Fair value - Derivative Assets	275	307
Fair value - Derivative Liabilities	261	278
Nondesignated \| Customer Accommodation \| TBAs
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	18	18
Fair value - Derivative Assets	0	0
Fair value - Derivative Liabilities	0	0
Nondesignated \| Customer Accommodation \| Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	15,231	13,205
Fair value - Derivative Assets	135	148
Fair value - Derivative Liabilities	$ 131	$ 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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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
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-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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