COMMITMENTS AND CONTINGENCIES: (Details 3) PEN in Millions, $ in Millions	1 Months Ended		6 Months Ended		12 Months Ended
	Jul. 31, 2014	Jun. 30, 2014	Jun. 30, 2015 PEN item T MW	Jun. 30, 2015 USD ($) item T MW	Dec. 31, 2014 PEN	Dec. 31, 2014 USD ($)	Dec. 31, 2005 item	Dec. 31, 1997
Mexico
Other commitments:
Commitment for capital projects				$ 260.8
Tia Maria | Peru
Other commitments:
Project Budget				1,400.0
Amount expended in current year				$ 359.4
Annual production ( in tons) | T			120,000	120,000
Toquepala Concentrator Expansion | Peru
Other commitments:
Project Budget				$ 1,200.0
Amount expended in current year				354.6
Amount committed to funding for social and infrastructure improvement projects					PEN 100	$ 33.0
Amount paid-out for development projects in the Candarave province			PEN 445	$ 143.0
MGE
Other commitments:
Number of power plants | item							2
Percentage of supply to third-party energy users			12.00%	12.00%
MGE | Mexico
Other commitments:
Number of power plants | item			2	2
Net total capacity (in megawatts) | MW			516.2	516.2
Copper | Toquepala Concentrator Expansion | Peru
Other commitments:
Estimated increase in annual production (in tons) | T			100,000	100,000
Molybdenum | Toquepala Concentrator Expansion | Peru
Other commitments:
Estimated increase in annual production (in tons) | T			3,100	3,100
Enersur | Power purchase agreements
Other commitments:
Term of power purchase agreement related to sale of power plant								20 years
Electroperu S.A | Power purchase agreements
Other commitments:
Term of power purchase agreement related to sale of power plant		20 years
Kallpa | Power purchase agreements
Other commitments:
Term of power purchase agreement related to sale of power plant	10 years