Postretirement Benefit Plans - Company's Asset Allocations for its U.K. Pension Plans by Asset Category (Detail) - United Kingdom [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total	$ 21,425	$ 22,858	$ 22,204
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	833	1,176
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	18,623	19,441
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	1,969	2,241
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	833	1,176
Cash [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	833	1,176
Pooled Pension Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	12,397	15,322
Pooled Pension Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	12,397	15,322
Pooled Fixed Pension Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	5,740	3,642
Pooled Fixed Pension Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	5,740	3,642
Real Estate Pooled Pension Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	486	477
Real Estate Pooled Pension Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	486	477
Insurance Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	1,969	2,241
Insurance Contracts [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total	$ 1,969	$ 2,241