Loans - Changes in Troubled Debt Restructurings (Detail) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2018 USD ($) Loan	Dec. 31, 2017 USD ($) Loan
Receivables [Abstract]
Number of Loans \| Loan	3	3
Principal paydowns, Recorded Investment	$ (49)
Post-Modification Outstanding Recorded Investment	$ 2,998	$ 3,047

Financing Receivable, Modifications, Collections During Period

No definition available.

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- Definition

Number of financing receivables that have been 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

+ Details

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Period Type:	duration

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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