Employee Benefit Plans - Reclassifications from Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Amortization of actuarial loss - total before tax	$ 762
Tax benefit	(283)	$ (330)	$ (156)
Net of tax	$ 479	$ 557	$ 263