Esop - Summary of Shares Held by Employee Stock Ownership Plan (ESOP) (Detail) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Accrued for allocation to participants	32,465
Earned ESOP shares	101,654	101,654
Unearned ESOP shares	465,881	498,346
Total ESOP shares	600,000	600,000
Fair value of unearned shares	$ 6,731,980	$ 6,707,737

No definition available.

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- Definition

Fair value of unearned shares held by the employee stock ownership plan (ESOP).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=65895303&loc=d3e17540-113929

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- Definition

The shares or units in an ESOP trust that have been assigned to individual participant accounts based on a known formula. IRS rules require allocations to be nondiscriminatory generally based on compensation, length of service, or a combination of both. For any particular participant such shares or units may be vested, unvested, or partially vested.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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- Definition

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
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- Definition

Number of allocated shares held by the Employee Stock Option Plan at balance sheet date. Allocated shares are shares that have been assigned to individual participant accounts based on a known formula.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Section 50
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- Definition

Number of shares of capital stock issued (purchased by employees) in connection with an employee stock ownership plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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