Retirement Plans - Net Periodic Pension (Income) Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Net settlement loss	$ 2,400		$ 1,900
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	3,423	$ 3,577	3,376
Expected return on plan assets	(4,627)	(5,597)	(5,197)
Recognized net actuarial loss	917	470	839
Net settlement loss	2,356		1,878
Total net periodic pension (income) expense	$ 2,069	$ (1,550)	$ 896