Income Taxes - Deferred Tax Assets Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Employee and retiree benefit plans	$ 28,097	$ 27,615
Capital loss and other carryforwards	16,035	12,754
Operating lease assets	20,036
Operating lease liabilities	(19,530)
Depreciation and amortization	(175,904)	(168,485)
Inventories	7,699	5,969
Allowances and accruals	7,765	11,540
Interest rate exchange agreement	2,113	3,543
Other	(14,998)	(6,388)
Total gross deferred tax (liabilities)	(128,687)	(113,452)
Valuation allowance	(16,035)	(12,754)
Total deferred tax (liabilities), net of valuation allowances	$ (144,722)	$ (126,206)