Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Reserves	$ 3,720	$ 3,145
Environmental	10,795	11,189
Compensation	3,957	6,782
Post-retirement benefits	2,133	12,570
Research & development expenses		6,787
Inventories	(35)	1,891
Tax carryforwards	21,843	21,988
Other	3,506	2,106
Deferred tax assets	45,919	66,458
Valuation allowance	(30,029)	(7,405)
Net deferred tax assets	15,890	59,053
Property	(66,426)	(98,809)
Intangible assets	(22,231)	(17,647)
Pension	(3,890)	(21,941)
Other	(1,935)	(4,110)
Deferred tax liabilities	(94,482)	(142,507)
Net deferred tax liabilities	$ (78,592)	$ (83,454)