REVENUE: - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue Recognition
Net sales	$ 2,930.9	$ 2,505.6	$ 8,649.0	$ 7,600.2
Corporate, other and eliminations
Revenue Recognition
Net sales	(46.6)	(46.2)	(140.1)	(123.0)
Mexican Open-Pit | Operating segment
Revenue Recognition
Net sales	1,602.7	1,462.2	4,807.2	4,400.3
Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	184.9	153.6	516.6	474.3
Peruvian Operations | Operating segment
Revenue Recognition
Net sales	1,189.9	936.0	3,465.4	2,848.6
Copper
Revenue Recognition
Net sales	2,261.0	1,874.6	6,671.4	5,804.9
Copper | Corporate, other and eliminations
Revenue Recognition
Net sales	(18.0)	(22.2)	(60.9)	(56.5)
Copper | Mexican Open-Pit | Operating segment
Revenue Recognition
Net sales	1,284.1	1,118.1	3,837.3	3,501.4
Copper | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	26.9	23.7	96.2	65.1
Copper | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	968.1	755.0	2,798.8	2,294.9
Molybdenum
Revenue Recognition
Net sales	296.8	343.1	949.6	899.1
Molybdenum | Mexican Open-Pit | Operating segment
Revenue Recognition
Net sales	153.3	230.3	511.2	561.5
Molybdenum | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	143.5	112.8	438.4	337.6
Silver
Revenue Recognition
Net sales	151.7	104.0	420.5	317.8
Silver | Corporate, other and eliminations
Revenue Recognition
Net sales	(22.7)	(22.0)	(70.7)	(59.4)
Silver | Mexican Open-Pit | Operating segment
Revenue Recognition
Net sales	85.7	62.4	243.8	181.9
Silver | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	48.3	40.1	136.0	121.1
Silver | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	40.4	23.5	111.4	74.2
Zinc
Revenue Recognition
Net sales	113.0	70.0	298.0	225.1
Zinc | Corporate, other and eliminations
Revenue Recognition
Net sales	(4.8)	0.2	(4.3)	0.5
Zinc | Mexican Open-Pit | Operating segment
Revenue Recognition
Net sales	28.5		77.6
Zinc | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	89.3	69.8	224.7	224.6
Other
Revenue Recognition
Net sales	108.4	113.9	309.7	353.3
Other | Corporate, other and eliminations
Revenue Recognition
Net sales	(1.1)	(2.2)	(4.1)	(7.6)
Other | Mexican Open-Pit | Operating segment
Revenue Recognition
Net sales	51.2	51.4	137.3	155.5
Other | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	20.4	20.0	59.8	63.5
Other | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	$ 38.0	$ 44.7	$ 116.7	$ 141.9