Employee Benefits - Summary of Nonvested Common Stock Awards and Changes During Period (Detail)	9 Months Ended
Sep. 30, 2016 $ / shares shares
Common Stock Awards
Nonvested common stock awards, Beginning balance \| shares	129,053
Granted \| shares	143,528
Vested \| shares	(109,473)
Forfeited \| shares	(1,183)
Nonvested common stock awards, Ending balance \| shares	161,925
Weighted Average Grant Date Fair Market Value Per Share
Nonvested common stock awards, Beginning balance \| $ / shares	$ 21.52
Granted \| $ / shares	26.98
Vested \| $ / shares	21.48
Forfeited \| $ / shares	24.97
Nonvested common stock awards, Ending balance \| $ / shares	$ 26.37

Gross number of share options (or share units) granted during the period.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Number of non-vested options outstanding.

+ References

No definition available.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Number of non-vested options forfeited.

+ References

No definition available.

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- Definition

Weighted average grant-date fair value of non-vested options forfeited.

+ References

No definition available.

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- Definition

Weighted average grant-date fair value of non-vested options outstanding.

+ References

No definition available.

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- Definition

Number of options vested.

+ References

No definition available.

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- Definition

Weighted average grant-date fair value of options vested.

+ References

No definition available.

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