Income Taxes - Schedule Showing Tax Effects of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Tax Liabilities:
Depreciation	$ (63,104)	$ (57,113)
Amortization of intangibles		(49)
Unrealized foreign exchange loss	(838)	(910)
Other	(1,159)	(823)
Deferred Tax Liabilities, Gross	(65,101)	(58,895)
Deferred Tax Assets:
Pensions	18,775	5,640
Deferred revenue	1,650	3,058
Other accruals and reserves	13,230	12,061
Inventories	1,957	1,158
Legal and environmental accruals	9,505	6,594
Deferred compensation	15,636	20,510
Bad debt and rebate reserves	4,618	3,018
Subsidiaries net operating loss carryforwards	727	899
Tax credit carryforwards	2,064	915
Deferred Tax Assets, Gross	68,162	53,853
Valuation Allowance	(1,506)	(1,302)
Net Deferred Tax (Liabilities) Assets	1,555	(6,344)
Reconciliation to Consolidated Balance Sheet:
Current deferred tax assets	15,364	12,637
Non-current deferred tax assets (in other non-current assets)	2,044	1,658
Current deferred tax liabilities (in accrued liabilities)	(49)	(23)
Non-current deferred tax liabilities	(15,804)	(20,616)
Net Deferred Tax (Liabilities) Assets	$ 1,555	$ (6,344)