SUPPLEMENTARY DATA - QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Information [Abstract]
Net sales	$ 307,809		$ 308,836	$ 376,067		$ 402,059		$ 383,277	$ 449,579	$ 523,731	$ 538,940	$ 2,163,595	$ 1,394,771	$ 1,895,527	$ 2,163,595
Gross Profit	17,809		26,153	51,053		42,794		24,254	43,639	20,773	51,977		137,809	140,643	295,190
Net Income (Loss) Attributable to Parent	$ (51,160)		$ (31,476)	$ 6,771	[1]	$ 232	[2]	$ (53,046)	$ (9,067)	$ (20,511)	$ 2,163		$ (75,633)	$ (80,461)	$ 35,205
Earnings Per Share [Abstract]
Earnings Per Share, Basic	$ (1.07)	[3]	$ (0.79)	$ 0.17	[1]	$ (0.05)	[2]	$ (1.58)	$ (0.47)	$ (0.40)	$ 0.02		$ (1.74)	$ (2.43)	$ 0.66
Earnings Per Share, Diluted	$ (1.07)	[3]	$ (0.79)	$ 0.17	[1]	$ (0.05)	[2]	$ (1.58)	$ (0.47)	$ (0.40)	$ 0.02		$ (1.74)	$ (2.43)	$ 0.64
Mining asset impairment and inventory writedown													$ 0	$ 39,932	$ 0
Noncash goodwill impairment charge													$ 0	$ 36,571	$ 0

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[2] (a) Mining asset impairment and inventory write-down of 34.8 million was included in the quarter ended June 30, 2014.

[3] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmNkN2QzMThhNmU4MDRiZTQ5M2FmNjkwN2RhZTlhNjAxfFRleHRTZWxlY3Rpb246QTdFNDcyRkEzMkE5MUMwN0E2RjBFRURDRkEwM0QzNTgM}