Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Revenues	$ 354,721	$ 371,483
Costs, expenses and other:
Cost of sales	273,802	301,711
Depreciation, depletion and amortization	35,013	38,059
Selling and administrative	31,672	26,716
Heritage health benefit expenses	3,015	3,059
Loss on sale/disposal of assets	336	229
Restructuring charges	0	553
Derivative loss (gain)	2,600	(5,276)
Income from equity affiliates	(1,293)	(2,025)
Other operating loss (gain)	(1,962)	2
Total costs, expenses and other	343,183	363,028
Operating income	11,538	8,455
Other income (expense):
Interest expense	(29,669)	(24,735)
Interest income	1,791	2,140
Gain (loss) on foreign exchange	(1,387)	2,109
Other income (loss)	(122)	193
Total other income (expense)	(29,387)	(20,293)
Loss before income taxes	(17,849)	(11,838)
Income tax expense (benefit)	(47,935)	2,040
Net income (loss)	30,086	(13,878)
Less net loss attributable to noncontrolling interest	(498)	(2,146)
Net income (loss) applicable to common shareholders	$ 30,584	$ (11,732)
Net income (loss) per share applicable to common shareholders:
Basic and diluted (in dollars per share)	$ 1.67	$ (0.67)
Weighted average number of common shares outstanding:
Basic (shares)	18,262	17,621
Diluted (shares)	18,269	17,621