SEGMENT AND RELATED INFORMATION: (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Provisionally priced sales
Provisional price sales adjustment amounts included in accounts receivable	$ 6.6	$ (2.0)
Provisional price sales adjustment amounts included in net sales	6.6	(2.0)
Copper
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	19,700,000
Provisional price	3.59
Provisional price sales adjustment amounts included in accounts receivable	2.9	1.4
Provisional price sales adjustment amounts included in net sales	2.9	1.4
Copper | January 2013
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	19,700,000
Provisional price	3.59
Molybdenum
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	8,800,000
Provisional price	11.60
Provisional price sales adjustment amounts included in accounts receivable	3.7	(3.4)
Provisional price sales adjustment amounts included in net sales	$ 3.7	$ (3.4)
Molybdenum | January 2013
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	3,000,000
Provisional price	11.60
Molybdenum | February 2013
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	3,100,000
Provisional price	11.60
Molybdenum | March 2013
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	2,600,000
Provisional price	11.60
Molybdenum | April 2013
Provisionally priced sales
Nonmonetary notional amount of commodity (in million lbs.)	100,000
Provisional price	11.60