Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Reserves	$ 685	$ 991
Environmental	4,481	5,696
Compensation	2,415	3,287
Pension	4,279
Post-retirement benefits	1,388	1,619
Research & development expenses	3,092	6,439
Inventories		(91)
Tax carryforwards	16,703	25,227
Other	5,714	1,117
Deferred tax assets	38,757	44,285
Valuation allowance	(23,305)	(28,485)
Net deferred tax assets	15,452	15,800
Property	(70,492)	(65,027)
Intangible assets	(18,808)	(19,355)
Pension		(6,198)
Other	(3,282)	(1,577)
Deferred tax liabilities	(92,582)	(92,157)
Net deferred tax liabilities	$ (77,130)	$ (76,357)

Deferred tax assets inventory and deferred expense capitalized inventory costs.

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Deferred tax assets tax carryforwards.

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Deferred tax assets tax deferred expense environmental.

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Deferred tax liabilities pension and post retirement benefits.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs expensed in connection with a business combination.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from pension benefits.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from postretirement benefits.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences from reserves, classified as other.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting.

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Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill.

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Amount of deferred tax liability attributable to taxable temporary differences classified as other.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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