Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Pension, postretirement and other benefits	$ 48,589	$ 51,736
Capitalized expenditures	2,908	3,186
Deferred Tax Assets, Capital Loss Carryforwards	0	13,780
Net operating loss and tax credit carryforwards	167,719	157,319
Deferred Tax Assets, Property, Plant and Equipment	20,599	0
Deferred Tax Assets, Goodwill and Intangible Assets	4,220	2,122
All other items	49,394	44,999
Total deferred tax assets	293,429	273,142
Deferred tax liabilities:
Property, plant and equipment	(19,479)	(23,312)
Operating lease right-of-use	(20,599)	0
All other items	(12,680)	(13,221)
Total deferred tax liabilities	(52,758)	(36,533)
Valuation allowances	(194,794)	(171,126)
Net deferred tax assets	$ 45,877	$ 65,483