Loans and Allowance for Loan Losses - Summary of Subsequent Default (Detail)	3 Months Ended	6 Months Ended
Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) contract	Jun. 30, 2020 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract			2	1
Recorded Investment	$ 0	$ 0	$ 468,000	$ 1,317,000
Troubled debt restructurings that subsequently defaulted	$ 0	$ 0	$ 468,000	$ 1,317,000
Business banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract			1	0
Recorded Investment			$ 411,000	$ 0
Troubled debt restructurings that subsequently defaulted			$ 411,000	$ 0
Consumer home equity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract			1	1
Recorded Investment			$ 57,000	$ 1,317,000
Troubled debt restructurings that subsequently defaulted			$ 57,000	$ 1,317,000

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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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