Loans and Allowance for Loan Losses - Schedule of Loans by Class Modified as Troubled Debt Restructuring (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($) SecurityLoan	Jun. 30, 2017 USD ($) SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	6	27
Pre-modification Outstanding Recorded Investment	$ 3,231	$ 29,733
Post-modification Outstanding Recorded Investment	$ 3,231	$ 29,733
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan		10
Pre-modification Outstanding Recorded Investment		$ 17,429
Post-modification Outstanding Recorded Investment		$ 17,429
Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	2	6
Pre-modification Outstanding Recorded Investment	$ 1,084	$ 9,442
Post-modification Outstanding Recorded Investment	$ 1,084	$ 9,442
Other [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	2
Pre-modification Outstanding Recorded Investment	$ 1,213
Post-modification Outstanding Recorded Investment	$ 1,213
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	1	6
Pre-modification Outstanding Recorded Investment	$ 502	$ 938
Post-modification Outstanding Recorded Investment	$ 502	$ 938
Consumer - Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| SecurityLoan	1	5
Pre-modification Outstanding Recorded Investment	$ 432	$ 1,924
Post-modification Outstanding Recorded Investment	$ 432	$ 1,924

The number of loans included in the loan portfolio.

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- Definition

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+ References

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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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- Definition

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

+ References

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