Allowance for Loan Losses - Additional Information (Detail) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recovery of loan losses	$ (1,351,000)	$ (4,934,000)
Loans modified as TDRs	0	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recovery of loan losses	$ 455,000
Overstated \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for acquired loans		$ 580,000

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

Amount of addition to allowance reserve for credit loss arising from purchase of loan and lease portfolios.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
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-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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-Name Accounting Standards Codification
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-SubTopic 220
-Section S99
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