RELATED PARTY TRANSACTIONS: (Details) $ in Millions	1 Months Ended		12 Months Ended
	May 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)	Dec. 31, 2012 item MW	Dec. 31, 2014 item
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			$ 33.3	$ 49.1
Related parties payable:			120.2	103.3
Total purchases			534.6	454.4	$ 576.3
Total sales			$ 2.1	2.0	1.9
Equity investment in affiliate
RELATED PARTY TRANSACTIONS:
Ownership percentage			44.20%
Apu Coropuna S.R.L.
RELATED PARTY TRANSACTIONS:
Ownership percentage			30.00%
Minimum
RELATED PARTY TRANSACTIONS:
Aggregate consideration of Material Affiliate Transaction to be be authorized by the General Counsel and CFO			$ 8.0
Maximum
RELATED PARTY TRANSACTIONS:
Aggregate consideration of Material Affiliate Transaction to be be authorized by the General Counsel and CFO			10.0
Grupo Mexico and affiliates
RELATED PARTY TRANSACTIONS:
Total purchases			2.7	2.5	4.1
Total sales			213.0	160.5	132.9
Asarco LLC ("Asarco")
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			9.2	10.0
Related parties payable:			23.8	14.9
Total purchases			66.3	31.3	233.9
Total sales			48.0	33.4	77.9
Accounts Receivable		$ 62.0
Making quarterly payments		$ 0.5
Asarco LLC ("Asarco") | Other Noncurrent Assets [Member]
RELATED PARTY TRANSACTIONS:
Related parties receivable					2.2
Asarco LLC ("Asarco") | London Interbank Offered Rate (LIBOR) [Member]
RELATED PARTY TRANSACTIONS:
Debt Instrument, Basis Spread on Variable Rate		2.00%
Americas Mining Corporation
RELATED PARTY TRANSACTIONS:
Related parties receivable current:				0.1
Total sales				0.1
AMMINCO Apoyo Administrativo, S.A. de C.V. ("AMMINCO")
RELATED PARTY TRANSACTIONS:
Related parties payable:			5.0	9.5
Total purchases			10.0	8.9	18.6
Total sales				0.1	0.1
AMMINCO Apoyo Administrativo, S.A. de C.V. ("AMMINCO") | Maximum
RELATED PARTY TRANSACTIONS:
Related parties receivable current:				0.1
Compania Perforadora Mexico S.A.P.I. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			0.3	0.3
Eolica El Retiro, S.A.P.I. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties payable:			0.4	2.7
Total purchases			$ 3.0	$ 9.3	1.0
Number of wind turbines | item							37
Percentage of supply to third-party energy users			27.00%	61.00%
Ferrocarril Mexicano, S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties payable:			$ 5.6	$ 4.0
Total purchases			42.9	41.8	45.8
Grupo Mexico
RELATED PARTY TRANSACTIONS:
Total purchases					10.0
Donations			3.5	0.9	7.1
Grupo Mexico Servicios
RELATED PARTY TRANSACTIONS:
Related parties payable:			20.2	11.1
Total purchases			20.1	20.1
Intermodal Mexico S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Total purchases				0.5
MGE
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			23.4	38.4
Related parties payable:			57.5	57.2
Total purchases			331.0	287.3	213.3
Total sales			$ 165.0	$ 126.9	54.9
Accounts Receivable	$ 97.2
Making quarterly payments	$ 5.1
Debt Instrument, Basis Spread on Variable Rate	8.28%
MGE | Mexico
RELATED PARTY TRANSACTIONS:
Number of natural gas-fired combined cycle power generating units | item						2
Net total capacity (in megawatts) | MW						516.2
Percentage of supply to third-party energy users			1.40%	2.00%
Mexico Compania Constructora S.A de C.V.
RELATED PARTY TRANSACTIONS:
Related parties payable:			$ 5.9	$ 2.0
Total purchases			43.8	44.5	42.6
Peru Mining Exploration And Development Company
RELATED PARTY TRANSACTIONS:
Total purchases				$ 0.4
Number of mining concessions purchased | item				3
Grupo Mexico Servicios de Ingenieria, S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			0.2	$ 0.2
Related parties payable:			1.2	0.9
Total purchases			16.7	10.3	11.1
Controladora de Infraestructura Energetica Mexico, S. A. de C. V.
RELATED PARTY TRANSACTIONS:
Total purchases			0.8
Boutique Bowling de Mexico, S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			0.1	0.1
Related parties payable:			0.3	0.3
Total purchases			0.4	0.3	0.4
Total sales			0.1	0.1	0.1
Mexico Transportes Aereos S.A. de C.V. ("Mextransport")
RELATED PARTY TRANSACTIONS:
Related parties payable:			0.1	0.5
Total purchases			2.1	1.8	3.5
Total sales			1.9	1.8	1.7
Operadora de Cinemas S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties receivable current:			0.1
Related parties payable:			0.2	0.2
Total purchases			0.2	0.4	0.2
Total sales			$ 0.1	$ 0.1	$ 0.1