Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Shares Under Option
Shares Under Option, Outstanding, Beginning balance | shares	668,667
Shares Under Option, Granted | shares	160,312
Shares Under Option, Expired | shares	0
Shares Under Option, Forfeited | shares	(62,537)
Shares Under Option, Exercised | shares	(261,534)
Share Under Option, Outstanding, Ending balance | shares	504,908
Shares Under Options, Exercisable at December 31 | shares	195,968
Weighted Average Exercise Price Per Share [Abstract]
Weighted Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 18.88
Weighted Average Exercise Price Per Share, Granted | $ / shares	19.73
Weighted Average Exercise Price Per Share, Expired | $ / shares	0.00
Weighted Average Exercise Price Per Share, Forfeited | $ / shares	18.93
Weighted Average Exercise Price Per Share, Exercised | $ / shares	19.04
Weighted Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	19.06
Weighted Average Exercise Price Per Share, Exercisable at December 31, 2016 | $ / shares	$ 19.24
Weighted Average Remaining Contractual Life, Outstanding at December 31, 2016	6 years 2 months 12 days
Weighted Average Remaining Contractual Life, Exercisable at December 31, 2016	3 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding at December 31, 2016 | $	$ 5,979
Aggregate Intrinsic Value, Exercisable at December 31, 2016 | $	$ 2,285