Pension and Other Postretirement Benefits - Contributions for Pension and Other Postretirement Benefits (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Foreign Defined Benefit Pension Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contributions	$ 424	$ 430
Other Postretirement Benefit Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contributions	275	241
U.K. Defined Contribution Pension Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contributions	65	62
U.S. Defined Contribution Plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contributions	$ 650	$ 503