REVENUE: - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
REVENUE:
Net sales	$ 4,289.0	$ 3,051.0	$ 8,540.4	$ 6,172.9
Operating segment
REVENUE:
Net sales	4,364.3	3,112.3	8,707.7	6,283.1
Corporate, Other & Eliminations
REVENUE:
Net sales	(75.4)	(61.3)	(167.3)	(110.2)
Mexican Open-pit \| Operating segment
REVENUE:
Net sales	2,511.9	1,754.8	4,955.5	3,504.2
Mexican IMMSA Unit \| Operating segment
REVENUE:
Net sales	267.9	179.3	586.5	334.7
Peruvian Operations \| Operating segment
REVENUE:
Net sales	1,584.4	1,178.2	3,165.8	2,444.2
Copper
REVENUE:
Net sales	3,116.8	2,259.5	6,099.4	4,691.5
Copper \| Operating segment
REVENUE:
Net sales	3,144.2	2,281.0	6,152.8	4,731.2
Copper \| Corporate, Other & Eliminations
REVENUE:
Net sales	(27.3)	(21.5)	(53.4)	(39.7)
Copper \| Mexican Open-pit \| Operating segment
REVENUE:
Net sales	1,859.4	1,319.0	3,612.1	2,698.3
Copper \| Mexican IMMSA Unit \| Operating segment
REVENUE:
Net sales	49.2	36.3	91.6	57.6
Copper \| Peruvian Operations \| Operating segment
REVENUE:
Net sales	1,235.6	925.7	2,449.1	1,975.2
Molybdenum
REVENUE:
Net sales	475.8	354.7	921.3	655.2
Molybdenum \| Operating segment
REVENUE:
Net sales	475.8	354.7	921.3	655.2
Molybdenum \| Mexican Open-pit \| Operating segment
REVENUE:
Net sales	266.3	192.2	496.3	356.6
Molybdenum \| Peruvian Operations \| Operating segment
REVENUE:
Net sales	209.5	162.4	425.0	298.6
Silver
REVENUE:
Net sales	375.8	201.9	907.3	378.5
Silver \| Operating segment
REVENUE:
Net sales	418.4	226.8	1,007.2	426.0
Silver \| Corporate, Other & Eliminations
REVENUE:
Net sales	(42.6)	(24.9)	(99.9)	(47.6)
Silver \| Mexican Open-pit \| Operating segment
REVENUE:
Net sales	214.2	115.6	535.6	215.9
Silver \| Mexican IMMSA Unit \| Operating segment
REVENUE:
Net sales	117.0	60.6	281.6	110.1
Silver \| Peruvian Operations \| Operating segment
REVENUE:
Net sales	87.3	50.6	190.0	100.0
Zinc
REVENUE:
Net sales	152.2	123.1	297.2	234.5
Zinc \| Operating segment
REVENUE:
Net sales	155.8	136.8	307.8	255.7
Zinc \| Corporate, Other & Eliminations
REVENUE:
Net sales	(3.6)	(13.7)	(10.6)	(21.2)
Zinc \| Mexican Open-pit \| Operating segment
REVENUE:
Net sales	76.3	74.5	141.0	126.0
Zinc \| Mexican IMMSA Unit \| Operating segment
REVENUE:
Net sales	79.5	62.3	166.8	129.7
Other
REVENUE:
Net sales	168.3	111.9	315.1	213.3
Other \| Operating segment
REVENUE:
Net sales	170.1	113.0	318.5	215.1
Other \| Corporate, Other & Eliminations
REVENUE:
Net sales	(1.8)	(1.1)	(3.4)	(1.8)
Other \| Mexican Open-pit \| Operating segment
REVENUE:
Net sales	95.8	53.4	170.5	107.4
Other \| Mexican IMMSA Unit \| Operating segment
REVENUE:
Net sales	22.3	20.1	46.4	37.3
Other \| Peruvian Operations \| Operating segment
REVENUE:
Net sales	$ 52.0	$ 39.5	$ 101.6	$ 70.4