COMMITMENTS AND CONTINGENCIES: - Others (Details) S/ in Millions			1 Months Ended				3 Months Ended
	Feb. 20, 2020 MW	Jul. 15, 2019 complaint	Jun. 30, 2018 USD ($) T	May 31, 2016 MW	Jul. 31, 2014 MW	Jun. 30, 2014 MW	Mar. 31, 2020 USD ($) item person km T	Mar. 31, 2020 PEN (S/) item person km T
Other commitments:
Commitment for capital projects							$ 252,500,000
Tia Maria | Peru
Other commitments:
Number of kilometer industrial railway built | km							32	32
Project budget							$ 1,400,000,000
Number Of Complaints | complaint		3
Amount spend as of the current date							$ 340,600,000
Annual production ( in tons) | T							120,000	120,000
Number of workers expected to be directly employed | item							600	600
Number of workers expected to be indirectly employed | item							4,200	4,200
Toquepala Concentrator Expansion | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects							$ 129,300,000	S/ 445.0
Commitment liability recorded in the balance sheet							59,100,000
Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects							$ 290,700,000	S/ 1,000.0
Copper | Michiquillay | Peru
Other commitments:
Annual production ( in tons) | T			225,000
Contingent contractual obligation			$ 400,000,000
Estimated mineralized material (in tons) | T			1,150,000,000
Copper grade percentage			0.63%
Initial mine life			25 years
Contractual obligation paid on project			$ 12,500,000
Remaining amount to pay if project is developed			$ 387,500,000
Educational Project | Tia Maria | Peru
Other commitments:
Number of persons got benefits from the programs | person							700	700
Number of jobs expected to be generated | person							9,000	9,000
Number of Direct Jobs Expected to be Generated | person							3,600	3,600
Number of Indirect Jobs Expected to be Generated | person							5,400	5,400
Educational Project | Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects							$ 31,500,000	S/ 108.4
Water Treatment | Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects							22,700,000	78.0
Social Investment For Taxes | Toquepala Concentrator Expansion | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects							$ 20,400,000	S/ 70.3
Number of Infrastructure Projects Agreed for Construction | item							1	1
Social Investment For Taxes | Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects							$ 25,500,000	S/ 87.8
Number of Infrastructure Projects Agreed for Construction							2
Electroperu S.A | Power purchase agreements | Peru
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW						120
Term of power purchase agreement related to sale of power plant						20 years
Parque Eolico de Fenicias, S. de R.L. de C.V | Power purchase agreements | Mexico
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW	611,400
Term of power purchase agreement related to sale of power plant	20 years
Kallpa | Power purchase agreements | Peru
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW					120
Term of power purchase agreement related to sale of power plant				10 years	10 years
Kallpa | Power purchase agreements | Peru | Maximum
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW				80