FINANCING: (Details) $ in Millions	12 Months Ended	118 Months Ended
	Dec. 31, 2024 USD ($) item grade	Apr. 30, 2015 USD ($) item	Dec. 31, 2023 USD ($)	Dec. 31, 2019 USD ($)
FINANCING
Face amount	$ 6,351.2	$ 6,200.0	$ 6,351.2
Issuance discount	(59.0)		(61.2)
Issuance costs	(33.9)		(35.4)
Long-term debt, Carrying Value	6,258.3		6,254.6
Less, current portion	499.8
Long-term debt, net of current portion	$ 5,758.5		6,254.6
Number of times for which senior unsecured notes were issued | item		8
Percentage of principal amount at which notes may be required to be repurchased in event of change of control in the entity	101.00%
Minimum
FINANCING
Number of decreased gradations that could cause a change of control triggering event | grade	1
3.875% Senior unsecured notes due 2025
FINANCING
Face amount	$ 500.0		500.0
Issuance discount	(0.1)		(0.4)
Issuance costs	(0.1)		(0.4)
Long-term debt, Carrying Value	$ 499.8		$ 499.2
Interest rate (as a percent)	3.875%		3.875%
9.250% Yankee Bonds due 2028
FINANCING
Face amount	$ 51.2		$ 51.2
Long-term debt, Carrying Value	$ 51.2		$ 51.2
Interest rate (as a percent)	9.25%		9.25%
9.250% Yankee Bonds due 2028 | Minera Mexico
FINANCING
Ratio of EBITDA to interest expense | item	2.5
9.250% Yankee Bonds due 2028 | Minera Mexico | Minimum
FINANCING
Ratio of EBITDA to interest expense	1
7.500% Senior unsecured notes due 2035
FINANCING
Face amount	$ 1,000.0		$ 1,000.0
Issuance discount	(9.9)		(10.5)
Issuance costs	(6.6)		(7.0)
Long-term debt, Carrying Value	$ 983.5		$ 982.5
Interest rate (as a percent)	7.50%		7.50%
6.750% Senior unsecured notes due 2040
FINANCING
Face amount	$ 1,100.0		$ 1,100.0
Issuance discount	(6.1)		(6.3)
Issuance costs	(4.9)		(5.1)
Long-term debt, Carrying Value	$ 1,089.0		$ 1,088.6
Interest rate (as a percent)	6.75%		6.75%
5.250% Senior unsecured notes due 2042
FINANCING
Face amount	$ 1,200.0		$ 1,200.0
Issuance discount	(16.6)		(17.1)
Issuance costs	(5.5)		(5.7)
Long-term debt, Carrying Value	$ 1,177.9		$ 1,177.2
Interest rate (as a percent)	5.25%		5.25%
5.875% Senior unsecured notes due 2045
FINANCING
Face amount	$ 1,500.0		$ 1,500.0
Issuance discount	(14.7)		(15.1)
Issuance costs	(7.8)		(8.0)
Long-term debt, Carrying Value	$ 1,477.5		$ 1,476.9
Interest rate (as a percent)	5.875%		5.875%
4.500% Minera Mexico Senior unsecured notes due 2050
FINANCING
Face amount	$ 1,000.0		$ 1,000.0
Issuance discount	(11.6)		(11.8)
Issuance costs	(9.0)		(9.2)
Long-term debt, Carrying Value	$ 979.4		$ 979.0
Interest rate (as a percent)	4.50%		4.50%
4.500% Minera Mexico Senior unsecured notes due 2050 | Minera Mexico S.A. de C.V. Notes
FINANCING
Face amount				$ 1,000.0