Benefit Plans - Component of Net Periodic Pension Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Net actuarial loss	$ 30,140	$ 36,271
Deferred tax benefit	(12,647)	(15,118)
Total	$ 17,493	$ 21,153