REVENUE: - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenue Recognition
Net sales	$ 2,300.7	$ 2,306.9	$ 5,094.6	$ 5,070.7
Corporate, other and eliminations
Revenue Recognition
Net sales	(38.6)	(107.3)	(76.8)	(262.0)
Mexican Open-Pit \| Operating segment
Revenue Recognition
Net sales	1,311.2	1,337.0	2,938.1	2,983.2
Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	141.2	166.3	320.7	343.8
Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	886.9	910.9	1,912.6	2,005.7
Copper
Revenue Recognition
Net sales	1,782.5	1,797.8	3,930.3	3,952.7
Copper \| Corporate, other and eliminations
Revenue Recognition
Net sales	(17.1)	(82.1)	(34.3)	(211.9)
Copper \| Mexican Open-Pit \| Operating segment
Revenue Recognition
Net sales	1,042.7	1,114.0	2,383.3	2,482.4
Copper \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	21.9	28.0	41.4	50.4
Copper \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	735.0	737.9	1,539.9	1,631.8
Molybdenum
Revenue Recognition
Net sales	254.4	198.2	556.0	474.0
Molybdenum \| Mexican Open-Pit \| Operating segment
Revenue Recognition
Net sales	170.5	105.8	331.2	256.2
Molybdenum \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	83.9	92.4	224.8	217.8
Silver
Revenue Recognition
Net sales	98.7	81.3	213.8	179.6
Silver \| Corporate, other and eliminations
Revenue Recognition
Net sales	(18.9)	(0.7)	(37.4)	(1.0)
Silver \| Mexican Open-Pit \| Operating segment
Revenue Recognition
Net sales	54.2		119.5
Silver \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	38.2	82.0	81.0	180.6
Silver \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	25.2		50.7
Zinc
Revenue Recognition
Net sales	63.0	99.4	155.1	204.6
Zinc \| Corporate, other and eliminations
Revenue Recognition
Net sales	(0.3)	(20.8)	0.3	(42.4)
Zinc \| Mexican Open-Pit \| Operating segment
Revenue Recognition
Net sales		58.1		124.8
Zinc \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	63.3	36.8	154.8	73.8
Zinc \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales		25.3		48.4
Other
Revenue Recognition
Net sales	102.1	130.2	239.4	259.8
Other \| Corporate, other and eliminations
Revenue Recognition
Net sales	(2.3)	(3.7)	(5.4)	(6.7)
Other \| Mexican Open-Pit \| Operating segment
Revenue Recognition
Net sales	43.8	59.1	104.1	119.8
Other \| Mexican IMMSA Unit \| Operating segment
Revenue Recognition
Net sales	17.8	19.5	43.5	39.0
Other \| Peruvian Operations \| Operating segment
Revenue Recognition
Net sales	$ 42.8	$ 55.3	$ 97.2	$ 107.7