Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Shares Under Option
Shares Under Option, Outstanding, Beginning balance | shares	673,216
Shares Under Option, Granted | shares	114,500
Shares Under Option, Expired | shares	(80,550)
Shares Under Option, Forfeited | shares	(10,500)
Shares Under Option, Exercised | shares	(27,999)
Share Under Option, Outstanding, Ending balance | shares	668,667
Shares Under Options, Exercisable at December 31 | shares	369,502
Weighted Average Exercise Price Per Share [Abstract]
Weighted Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 19.46
Weighted Average Exercise Price Per Share, Granted | $ / shares	18.52
Weighted Average Exercise Price Per Share, Expired | $ / shares	24.26
Weighted Average Exercise Price Per Share, Forfeited | $ / shares	17.83
Weighted Average Exercise Price Per Share, Exercised | $ / shares	16.44
Weighted Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	18.88
Weighted Average Exercise Price Per Share, Exercisable at December 31, 2014 | $ / shares	$ 19.64
Weighted Average Remaining Contractual Life, Outstanding at December 31, 2014	5 years 5 months
Weighted Average Remaining Contractual Life, Exercisable at December 31, 2014	3 years 3 months
Aggregate Intrinsic Value, Outstanding at December 31, 2014 | $	$ 1,546
Aggregate Intrinsic Value, Exercisable at December 31, 2014 | $	$ 671