Employee Benefits - Summary of Nonvested Common Stock Awards and Changes During Period (Detail)	3 Months Ended
Mar. 31, 2017 $ / shares shares
Compensation and Retirement Disclosure [Abstract]
Nonvested common stock awards, Beginning balance \| shares	161,174
Granted \| shares	0
Vested \| shares	(9,561)
Forfeited \| shares	(362)
Nonvested common stock awards, Ending balance \| shares	151,251
Nonvested common stock awards, Beginning balance \| $ / shares	$ 26.36
Granted \| $ / shares	0
Vested \| $ / shares	21.79
Forfeited \| $ / shares	26.98
Nonvested common stock awards, Ending balance \| $ / shares	$ 26.65

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- Definition

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

+ References

No definition available.

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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.

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No definition available.

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- Definition

Number of non-vested options forfeited.

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No definition available.

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- Definition

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

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No definition available.

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- Definition

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

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No definition available.

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- Definition

Number of options vested.

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No definition available.

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Weighted average grant-date fair value of options vested.

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No definition available.

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