Loans and the Allowance for Credit Losses - TDRs Defaulted Later Restructured (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) Default	Dec. 31, 2019 USD ($) Default
Financing Receivable, Modifications [Line Items]
Number of Defaults \| Default	1	3
Recorded Investment \| $	$ 155	$ 204
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults \| Default	1	1
Recorded Investment \| $	$ 155	$ 95
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults \| Default		1
Recorded Investment \| $		$ 97
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults \| Default		1
Recorded Investment \| $		$ 12

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No definition available.

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- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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- Definition

Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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