Debt - Advances of Debt (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Federal Home Loan Bank advances	$ 35,000	$ 40,000
Adjustable Rate Hybrid \| Federal Home Loan Bank Advances One
Debt Instrument [Line Items]
Federal Home Loan Bank advances	$ 10,000
Originated	Apr. 12, 2013
Current Interest Rate	3.2575%
Maturity Date	Apr. 13, 2020
Fixed Rate Credit \| Federal Home Loan Bank Advances Six
Debt Instrument [Line Items]
Federal Home Loan Bank advances	$ 10,000
Originated	Dec. 30, 2016
Current Interest Rate	0.67%
Maturity Date	Feb. 28, 2017
Fixed Rate Credit \| Federal Home Loan Bank Advances Two
Debt Instrument [Line Items]
Federal Home Loan Bank advances	$ 5,000
Originated	Oct. 20, 2016
Current Interest Rate	0.49%
Maturity Date	Jan. 20, 2017
Fixed Rate Credit \| Federal Home Loan Bank Advances Three
Debt Instrument [Line Items]
Federal Home Loan Bank advances	$ 5,000
Originated	Dec. 21, 2015
Current Interest Rate	0.99%
Maturity Date	Jun. 15, 2017
Fixed Rate Credit \| Federal Home Loan Bank Advances Four
Debt Instrument [Line Items]
Federal Home Loan Bank advances	$ 5,000
Originated	Dec. 22, 2015
Current Interest Rate	1.08%
Maturity Date	Sep. 15, 2017

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Date the debt instrument was issued, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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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.

+ References

No definition available.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64702-112823

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: 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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