Retirement Plans - Components of Net Periodic Benefit Cost (Detail) - Domestic Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 16	$ 20	$ 28	$ 43
Interest cost	474	510	948	1,015
Recognized net actuarial loss	449	413	911	822
Net periodic benefit cost	$ 939	$ 943	$ 1,887	$ 1,880