REVENUE: - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue Recognition
Net sales	$ 3,377.3	$ 2,930.9	$ 9,550.2	$ 8,649.0
Operating segment
Revenue Recognition
Net sales	3,446.3	2,977.6	9,729.4	8,789.1
Corporate, Other & Eliminations
Revenue Recognition
Net sales	(69.0)	(46.6)	(179.2)	(140.1)
Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	1,944.9	1,602.7	5,449.0	4,807.2
Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	199.8	184.9	534.6	516.6
Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	1,301.6	1,189.9	3,745.8	3,465.4
Copper
Revenue Recognition
Net sales	2,447.2	2,261.0	7,138.7	6,671.4
Copper \| Operating segment
Revenue Recognition
Net sales	2,475.5	2,279.0	7,206.6	6,732.3
Copper \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(28.2)	(18.0)	(67.9)	(60.9)
Copper \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	1,441.0	1,284.1	4,139.3	3,837.3
Copper \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	36.3	26.9	94.0	96.2
Copper \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	998.1	968.1	2,973.4	2,798.8
Molybdenum
Revenue Recognition
Net sales	434.9	296.8	1,090.1	949.6
Molybdenum \| Operating segment
Revenue Recognition
Net sales	434.9	296.8	1,090.1	949.6
Molybdenum \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	229.4	153.3	586.0	511.2
Molybdenum \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	205.5	143.5	504.1	438.4
Silver
Revenue Recognition
Net sales	250.2	151.7	628.6	420.5
Silver \| Operating segment
Revenue Recognition
Net sales	282.0	174.4	708.0	491.2
Silver \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(31.8)	(22.7)	(79.4)	(70.7)
Silver \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	139.9	85.7	355.8	243.8
Silver \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	73.9	48.3	184.0	136.0
Silver \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	68.2	40.4	168.2	111.4
Zinc
Revenue Recognition
Net sales	126.5	113.0	361.0	298.0
Zinc \| Operating segment
Revenue Recognition
Net sales	134.1	117.8	389.8	302.2
Zinc \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(7.6)	(4.8)	(28.8)	(4.3)
Zinc \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	68.4	28.5	194.4	77.6
Zinc \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	65.7	89.3	195.4	224.7
Other
Revenue Recognition
Net sales	118.5	108.4	331.8	309.7
Other \| Operating segment
Revenue Recognition
Net sales	119.8	109.6	334.9	313.8
Other \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(1.3)	(1.1)	(3.1)	(4.1)
Other \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	66.2	51.2	173.6	137.3
Other \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	23.8	20.4	61.2	59.8
Other \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	$ 29.7	$ 38.0	$ 100.1	$ 116.7