Income Taxes - Deferred Income Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Deferred tax assets related to uncertain tax positions	$ 8,700	$ 8,000
Deferred income tax assets:
Accrued liabilities	104,675	105,029
Retirement plans and postretirement benefits	33,259	38,004
Share-based compensation	15,386	16,261
Receivables and inventories	11,061	11,155
Intangible assets	4,131	0
Derivative financial instruments	3,990	1,646
State net operating loss carryforwards	30,799	35,089
State tax credit carryforwards	5,026	4,748
Valuation allowances	(10,968)	(13,177)
Deferred income tax assets	197,359	198,755
Deferred income tax liabilities:
Property, plant and equipment	(208,485)	(209,168)
Intangible assets	0	(29,612)
Cancellation of debt	(8,411)	(11,299)
Other	(1,162)	(843)
Deferred income tax liabilities	(218,058)	(250,922)
Net deferred income tax liability	$ (20,699)	$ (52,167)