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Employee Benefits - Summary of Nonvested Common Stock Awards and Changes During Period (Detail) | 6 Months Ended
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Jun. 30, 2017 $ / shares shares
Retirement Benefits [Abstract] |
Nonvested common stock awards, Beginning balance | shares | 161,174
Granted | shares | 101,241
Vested | shares | (57,816)
Forfeited | shares | (1,157)
Nonvested common stock awards, Ending balance | shares | 203,442
Nonvested common stock awards, Beginning balance | $ / shares | $ 26.36
Granted | $ / shares | 52.00
Vested | $ / shares | 26.30
Forfeited | $ / shares | 31.13
Nonvested common stock awards, Ending balance | $ / shares | $ 39.11

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- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
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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=96867065&loc=d3e5070-113901 + Details
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- Definition Number of non-vested options outstanding. + References No definition available. + Details
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- Definition Weighted average grant-date fair value of non-vested options forfeited. + References No definition available. + Details
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- Definition Weighted average grant-date fair value of non-vested options outstanding. + References No definition available. + Details
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