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Asset Purchases - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 13, 2013	Jul. 09, 2010
Business Acquisition [Line Items]
Amortization expense	$ 161	$ 161	$ 323
Amortization expense 2017	$ 245		$ 245
Hicksville [Member]
Business Acquisition [Line Items]
Recognition of core deposit intangible asset with acquired purchase					$ 1,090
Number of years amortized over an estimated remaining economic useful life of deposits	7 years
Amortization expense 2017	$ 78
Custar [Member]
Business Acquisition [Line Items]
Recognition of core deposit intangible asset with acquired purchase				$ 1,170
Number of years amortized over an estimated remaining economic useful life of deposits				7 years
Amortization expense 2017	$ 167

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- Definition

Amortized over estimated remaining economic useful life of deposits term.

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- Definition

Recognition of core deposit intangible asset with acquired purchase.

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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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.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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