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Federal Home Loan Bank Advances - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Loans	Dec. 31, 2016 USD ($)
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Total Borrowings	$ 5,000	$ 10,000
Number of FHLB Loans | Loans	1
Unsecured borrowings through correspondent banks	$ 69,000	58,000
Unpledged securities which could be sold or used as collateral	94,600	71,800
Additional borrowings available from the Federal Home Loan Bank based on current pledging	5,700	4,700
Maximum unsecured borrowing available	$ 116,800	115,700
FHLB Loan One [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Interest rate of loans	1.61%
Mortgage Loans at Cost [Member]
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Advances, secured by mortgage loans	$ 17,300	$ 17,900

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- Definition

Federal Home Loan Bank advances general debt obligations disclosures amount of available unused funds based on current pledging.

+ References

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Number of advances from FHLB.

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Unpledged securities.

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- Definition

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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- Definition

Discloses the single interest rate [if] applicable to the advances from the Federal Home Loan Bank, by branch, as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (b)
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- Definition

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
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- Definition

Amount of maximum advances or credit lines available from the Federal Home Loan Bank (FHLB).

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

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