Credit Quality - Summary of Subsequent Defaults (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Financing Receivable, Modifications [Line Items]
Number of contracts	314	201	679	496
Recorded Investment in Loans Modified in a TDR During the Period	$ 11	$ 42	$ 41	$ 51
Commercial Portfolio Segment \| Commercial and Industrial Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	5	2	7	3
Recorded Investment in Loans Modified in a TDR During the Period	$ 1	$ 28	$ 17	$ 29
Commercial Portfolio Segment \| Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications [Line Items]
Number of contracts	2		2	2
Recorded Investment in Loans Modified in a TDR During the Period	$ 1		$ 1	$ 0
Residential Mortgage Loans
Financing Receivable, Modifications [Line Items]
Number of contracts	53	62	129	110
Recorded Investment in Loans Modified in a TDR During the Period	$ 8	$ 13	$ 20	$ 20
Consumer Portfolio Segment \| Home Equity
Financing Receivable, Modifications [Line Items]
Number of contracts	1		5	2
Recorded Investment in Loans Modified in a TDR During the Period	$ 0		$ 0	$ 0
Consumer Portfolio Segment \| Credit Card
Financing Receivable, Modifications [Line Items]
Number of contracts	253	137	536	379
Recorded Investment in Loans Modified in a TDR During the Period	$ 1	$ 1	$ 3	$ 2

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

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