Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenues	$ 339,737	$ 355,854
Costs, expenses and other:
Cost of sales	284,604	281,125
Depreciation, depletion and amortization	36,567	37,015
Selling and administrative	30,426	27,399
Heritage health benefit expenses	3,298	3,015
(Gain) loss on sale/disposal of assets	(166)	336
Derivative (gain) loss	(2,384)	2,600
Income from equity affiliates	(1,520)	(1,293)
Other operating gain	0	(1,962)
Total costs, expenses and other	350,825	348,235
Operating (loss) income	(11,088)	7,619
Other (expense) income:
Interest expense	(29,261)	(28,927)
Interest income	893	1,791
Loss on foreign exchange	(467)	(1,387)
Other income (loss)	2,158	(122)
Total other income (expense)	(26,677)	(28,645)
Loss before income taxes	(37,765)	(21,026)
Income tax benefit	(465)	(47,935)
Net (loss) income	(37,300)	26,909
Less net loss attributable to noncontrolling interest	(499)	(498)
Net (loss) income applicable to common shareholders	$ (36,801)	$ 27,407
Net (loss) income per share applicable to common shareholders:
Basic and diluted (in dollars per share)	$ (1.98)	$ 1.50
Weighted average number of common shares outstanding:
Basic (in shares)	18,572	18,262
Diluted (in shares)	18,572	18,269