Stock-Based Compensation - Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Number of Shares
Options, Outstanding Beginning Balance (in shares) | shares	483,491
Options, Granted (in shares) | shares	123,500
Options, Exercised (in shares) | shares	(132,325)
Option, Expired (in shares) | shares	(19,516)
Options, Forfeited (in shares) | shares	(15,600)
Options, Outstanding Ending Balance (in shares) | shares	439,550
Options, Exercisable at end of period (in shares) | shares	214,375
Weighted-Average Exercise Price Per Share
Options, Beginning Balance (in dollars per share) | $ / shares	$ 20.08
Options, Granted (in dollars per share) | $ / shares	15.92
Options, Exercised (in dollars per share) | $ / shares	16.04
Options, Expired, (in dollars per share) | $ / shares	22.66
Options, Forfeited (in dollars per share) | $ / shares	18.54
Options, Ending Balance (in dollars per share) | $ / shares	20.07
Options, Exercisable at end of period (in dollars per share) | $ / shares	$ 20.24
Options, Outstanding at end of period, Weighted Average Remaining Contractual Life (Years)	4 years 4 months 24 days
Options, Exercisable at end of period, Weighted Average Remaining Contractual Life (Years)	3 years 3 months 18 days
Options, Outstanding at end of period, Aggregate Intrinsic Value | $	$ 2,414
Options, Exercisable at end of period, Aggregate Intrinsic Value | $	$ 1,141