Credit Quality and the Allowance for Loan and Lease Losses - Summary of Loans Modified in a TDR (Details) $ in Millions	3 Months Ended
Mar. 31, 2022 USD ($) loan	Mar. 31, 2021 USD ($) loan
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	2,742	3,797
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 177	$ 127
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	16	5
Charge-offs Recognized Upon Modification	$ 0	$ 0
Commercial \| Commercial and industrial loans
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	30	19
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 91	$ 6
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	13	1
Charge-offs Recognized Upon Modification	$ 0	$ 0
Commercial \| Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	5	1
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 4	$ 4
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	(1)	0
Charge-offs Recognized Upon Modification	$ 0	$ 0
Commercial \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan		3
Amortized Cost Basis of Loans Modified in a TDR During the Period		$ 25
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)		0
Charge-offs Recognized Upon Modification		$ 0
Residential Mortgage
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	260	178
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 42	$ 36
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	3	1
Charge-offs Recognized Upon Modification	$ 0	$ 0
Consumer \| Home equity
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	52	58
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 7	$ 3
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	(1)	(1)
Charge-offs Recognized Upon Modification	$ 0	$ 0
Consumer \| Indirect secured consumer loans
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	1,274	1,743
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 27	$ 43
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	0	1
Charge-offs Recognized Upon Modification	$ 0	$ 0
Consumer \| Credit card
Financing Receivable, Modifications
Number of Loans Modified in a TDR During the Period \| loan	1,121	1,795
Amortized Cost Basis of Loans Modified in a TDR During the Period	$ 6	$ 10
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)	2	3
Charge-offs Recognized Upon Modification	$ 0	$ 0

Amount of credit loss expense (reversal of expense) for financing receivable from change in methodology.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 11
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919244-210447

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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