SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES: (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 segment	Dec. 31, 2012	Dec. 31, 2011
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:
Average estimated recovery period of long-term leach stockpiles	5 years
Increase in total reserves at a property to qualify as a major expansion (as a percent)	10.00%
Period considered for calculation of average metal price	3 years
Current price of copper (in dollars per pound)	3.65	3.68	3.26
Average price of copper (in dollars per pound)	3.00
Average price of molybdenum (in dollars per pound)	10.00
Impairment in the carrying value of long-term assets	$ 0
Number of years of average prices for copper and molybdenum used for impairment analysis	3 years
Number of reportable segments	3
Financial information related to segments
Total property, net	6,476,168,000	5,156,731,000	4,429,900,000
Maximum
Financial information related to segments
Maximum period after shipping within which pricing is based by customer contracts in most cases	3 months
Estimated useful lives of buildings and equipment	40 years
Minimum
Financial information related to segments
Estimated useful lives of buildings and equipment	5 years
Mine development
Financial information related to segments
Total property, net	36,200,000	37,900,000
Mexican IMMSA Unit
Financial information related to segments
Number of underground poly metal mines	5
Total property, net	378,200,000	350,900,000	320,100,000
Peruvian Operations
Financial information related to segments
Number of open-pit copper mines	2
Total property, net	$ 2,451,400,000	$ 2,231,400,000	$ 2,225,900,000