Loans and Leases - Summary of Troubled Debt Restructurings by Class of Loans (Detail) $ in Millions	12 Months Ended
Dec. 31, 2021 USD ($) contract	Dec. 31, 2020 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	139	187
Pre-Modification Outstanding Recorded Investment	$ 30	$ 29
Post- Modification Outstanding Recorded Investment	$ 28	$ 17
Total commercial loans and leases
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	33	50
Pre-Modification Outstanding Recorded Investment	$ 22	$ 20
Post- Modification Outstanding Recorded Investment	$ 20	$ 9
Total commercial loans and leases \| Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	25	30
Pre-Modification Outstanding Recorded Investment	$ 21	$ 18
Post- Modification Outstanding Recorded Investment	$ 20	$ 8
Total commercial loans and leases \| Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	7	19
Pre-Modification Outstanding Recorded Investment	$ 1	$ 2
Post- Modification Outstanding Recorded Investment	$ 0	$ 1
Total commercial loans and leases \| Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	1	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post- Modification Outstanding Recorded Investment	$ 0	$ 0
Total consumer loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	106	137
Pre-Modification Outstanding Recorded Investment	$ 8	$ 9
Post- Modification Outstanding Recorded Investment	$ 8	$ 8
Total consumer loans \| Direct installment
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	38	68
Pre-Modification Outstanding Recorded Investment	$ 2	$ 4
Post- Modification Outstanding Recorded Investment	$ 2	$ 4
Total consumer loans \| Residential mortgages
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	27	24
Pre-Modification Outstanding Recorded Investment	$ 4	$ 3
Post- Modification Outstanding Recorded Investment	$ 4	$ 3
Total consumer loans \| Consumer lines of credit
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	41	45
Pre-Modification Outstanding Recorded Investment	$ 2	$ 2
Post- Modification Outstanding Recorded Investment	$ 2	$ 1

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Number of financing receivables that have been modified by troubled debt restructurings.

+ 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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