Retirement Plans - Components of Net Periodic Benefit Cost (Detail) - Domestic Plan [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 26	$ 27	$ 53	$ 70
Interest cost	474	508	1,422	1,523
Recognized net actuarial loss	456	412	1,367	1,236
Net periodic benefit cost	$ 956	$ 947	$ 2,842	$ 2,829