Pension Plans - Net Periodic Pension (Income) Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net settlement loss	$ 1,700	$ 2,400
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	3,173	3,423	$ 3,577
Expected return on plan assets	(4,131)	(4,627)	(5,597)
Recognized net actuarial loss	1,047	917	470
Net settlement loss	1,715	2,356
Total net periodic pension (income) expense	$ 1,804	$ 2,069	$ (1,550)