Pensions and Postretirement Benefits Other than Pensions - Assets of U.S and U.K Plans Using Fair Value Hierarchy (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total	$ 1,176,874	$ 1,146,430	$ 1,188,673
Domestic
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	8,491	724
Equity securities	531,939	520,202
Fixed income securities	307,911	315,588
Total	848,341	836,514	857,825
United Kingdom plan
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	1,078	917
Equity securities	60,185	65,391
Fixed income securities	220,974	214,762
Other investments	44,596	27,062
Total	326,833	308,132
Quoted Prices in Active Markets for Identical Assets Level (1) | Domestic
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	8,491	724
Equity securities	184,690	174,163
Fixed income securities	138,988	133,420
Total	332,169	308,307
Quoted Prices in Active Markets for Identical Assets Level (1) | United Kingdom plan
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	1,078	917
Equity securities	60,185	65,391
Fixed income securities	220,974	214,762
Other investments	0	0
Total	282,237	281,070
Significant Other Observable Inputs Level (2) | Domestic
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	0	0
Equity securities	347,249	346,039
Fixed income securities	168,923	182,168
Total	516,172	528,207
Significant Other Observable Inputs Level (2) | United Kingdom plan
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	0	0
Equity securities	0	0
Fixed income securities	0	0
Other investments	10,800	0
Total	10,800	0
Significant Unobservable Inputs Level (3)
Defined Benefit Plan Disclosure [Line Items]
Other investments		33,796	$ 27,062	$ 25,812
Significant Unobservable Inputs Level (3) | Domestic
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	0	0
Equity securities	0	0
Fixed income securities	0	0
Total	0	0
Significant Unobservable Inputs Level (3) | United Kingdom plan
Defined Benefit Plan Disclosure [Line Items]
Cash and cash equivalents	0	0
Equity securities	0	0
Fixed income securities	0	0
Other investments	33,796	27,062
Total	$ 33,796	$ 27,062