Income Taxes - Deferred Tax Assets Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Employee and retiree benefit plans	$ 42,950	$ 37,393
Capital loss carryforwards	18,668	0
Depreciation and amortization	(238,321)	(185,321)
Inventories	11,519	12,615
Allowances and accruals	9,338	12,528
Interest rate exchange agreement	10,442	12,948
Other	(90)	2,800
Total gross deferred tax (liabilities)	(145,494)	(107,037)
Capital loss valuation allowance	(18,668)	0
Total deferred tax (liabilities), net of valuation allowances	$ (164,162)	$ (107,037)