REVENUE: - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenue Recognition
Net sales	$ 3,051.0	$ 3,118.3	$ 6,172.9	$ 5,718.1
Operating segment
Revenue Recognition
Net sales	3,112.3	3,170.5	6,283.1	5,811.4
Corporate, Other & Eliminations
Revenue Recognition
Net sales	(61.3)	(52.1)	(110.2)	(93.4)
Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	1,754.8	1,738.5	3,504.2	3,204.4
Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	179.3	185.2	334.7	331.6
Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	1,178.2	1,246.7	2,444.2	2,275.4
Copper
Revenue Recognition
Net sales	2,259.5	2,366.6	4,691.5	4,410.4
Copper \| Operating segment
Revenue Recognition
Net sales	2,281.0	2,390.6	4,731.2	4,453.3
Copper \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(21.5)	(24.0)	(39.7)	(42.9)
Copper \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	1,319.0	1,347.1	2,698.3	2,553.3
Copper \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	36.3	41.8	57.6	69.3
Copper \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	925.7	1,001.7	1,975.2	1,830.7
Molybdenum
Revenue Recognition
Net sales	354.7	379.2	655.2	652.8
Molybdenum \| Operating segment
Revenue Recognition
Net sales	354.7	379.2	655.2	652.8
Molybdenum \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	192.2	213.3	356.6	357.8
Molybdenum \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	162.4	166.0	298.6	295.0
Silver
Revenue Recognition
Net sales	201.9	157.2	378.5	268.7
Silver \| Operating segment
Revenue Recognition
Net sales	226.8	183.6	426.0	316.8
Silver \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(24.9)	(26.3)	(47.6)	(48.0)
Silver \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	115.6	91.5	215.9	158.1
Silver \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	60.6	52.1	110.1	87.6
Silver \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	50.6	39.9	100.0	71.0
Zinc
Revenue Recognition
Net sales	123.1	114.9	234.5	185.0
Zinc \| Operating segment
Revenue Recognition
Net sales	136.8	115.0	255.7	184.5
Zinc \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(13.7)	(0.1)	(21.2)	0.6
Zinc \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	74.5	44.8	126.0	49.1
Zinc \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	62.3	70.1	129.7	135.4
Other
Revenue Recognition
Net sales	111.9	100.3	213.3	201.2
Other \| Operating segment
Revenue Recognition
Net sales	113.0	102.1	215.1	204.2
Other \| Corporate, Other & Eliminations
Revenue Recognition
Net sales	(1.1)	(1.8)	(1.8)	(3.0)
Other \| Mexican Open-pit \| Operating segment
Revenue Recognition
Net sales	53.4	41.8	107.4	86.1
Other \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	20.1	21.1	37.3	39.4
Other \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	$ 39.5	$ 39.2	$ 70.4	$ 78.8