Stock-Based Compensation - Reconciliation of Outstanding Balance of Stock Options (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options, Outstanding at beginning	475		490
Options granted	0	0	0	0
Options exercised	(17)		(32)
Options forfeited or expired	0		0
Options, Outstanding at ending	458		458
Options, Exercisable at ending	458		458
Weighted Average Exercise Price, Outstanding at beginning	$ 17.98		$ 17.73
Weighted Average Exercise Price, Granted	0		0
Weighted Average Exercise Price, Exercised	9.64		9.64
Weighted Average Exercise Price, Forfeited or expired	0		0
Weighted Average Exercise Price, Outstanding at ending	18.29		18.29
Weighted Average Exercise Price, Exercisable at ending	18.29		18.29
Weighted Average Grant Date Fair Value, Outstanding at beginning	8.76		8.69
Weighted Average Grant Date Fair Value, Granted	0		0
Weighted Average Grant Date Fair Value, Exercised	8.15		7.28
Weighted Average Grant Date Fair Value, Forfeited or expired	0		0
Weighted Average Grant Date Fair Value, Outstanding at ending	$ 8.79		$ 8.79
Aggregate Intrinsic Value, Outstanding	$ 6,260		$ 6,260
Aggregate Intrinsic Value, Exercisable	$ 6,260		$ 6,260