Allowance for Loan Losses and Credit Quality Information - Schedule of Loans Identified as Troubled Debt Restructurings During Periods Indicated (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Pre Modification	$ 10,250	$ 14,412
Post Modification	10,250	14,412
Owner-occupied commercial
Financing Receivable, Modifications [Line Items]
Pre Modification	0	3,071
Post Modification	0	3,071
Commercial mortgages
Financing Receivable, Modifications [Line Items]
Pre Modification	2,190	183
Post Modification	2,190	183
Commercial
Financing Receivable, Modifications [Line Items]
Pre Modification	5,102	954
Post Modification	5,102	954
Construction
Financing Receivable, Modifications [Line Items]
Pre Modification	920	6,054
Post Modification	920	6,054
Residential
Financing Receivable, Modifications [Line Items]
Pre Modification	557	1,652
Post Modification	557	1,652
Consumer loan commitments
Financing Receivable, Modifications [Line Items]
Pre Modification	1,481	2,498
Post Modification	$ 1,481	$ 2,498

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- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

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