Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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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
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Topic 230
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-Section 45
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-Name Accounting Standards Codification
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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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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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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Goodwill and Other Intangible Assets - Additional Information (Detail) $ in Thousands		12 Months Ended
	Sep. 30, 2016 Segment	Dec. 31, 2016 USD ($) Segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Goodwill [Line Items]
Amortization expense for other intangible assets \| $		$ 1,136	$ 1,118	$ 787
Goodwill impairment testing unit \| Community Banking
Goodwill [Line Items]
Number of reporting unit		1
Goodwill impairment testing unit \| Community Banking and Insurance Services [Member]
Goodwill [Line Items]
Number of reporting unit	2
Core deposit intangible assets
Goodwill [Line Items]
Weighted average remaining life of intangibles		7 years
Core deposit intangible assets \| Minimum
Goodwill [Line Items]
Remaining lives of intangibles		6 years
Core deposit intangible assets \| Maximum
Goodwill [Line Items]
Remaining lives of intangibles		9 years