PROVISIONALLY PRICED SALES: (Details) lb in Millions, $ in Millions	Jun. 30, 2016 USD ($) lb $ / item
Copper
PROVISIONALLY PRICED SALES:
Provisional price sales adjustment amounts included in accounts receivable and net sales | $	$ 5.8
Copper | July 2016 to September 2016
PROVISIONALLY PRICED SALES:
Sales volume (in million lbs.) | lb	182.6
Provisional price | $ / item	2.19
Molybdenum
PROVISIONALLY PRICED SALES:
Provisional price sales adjustment amounts included in accounts receivable and net sales | $	$ 14.5
Molybdenum | July 2016 to September 2016
PROVISIONALLY PRICED SALES:
Sales volume (in million lbs.) | lb	15.5
Provisional price | $ / item	7.13