STOCKHOLDERS' EQUITY: - Treasury Stock (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Activity in treasury stock
Balance at beginning of period	$ 9,636.7	$ 7,605.9	$ 9,238.1	$ 7,481.2
Balance at end of period	10,053.4	8,560.2	10,053.4	8,560.2
Treasury Stock
Activity in treasury stock
Balance at end of period	(2,371.9)	(2,946.2)	(2,371.9)	(2,946.2)
Treasury Stock | Parent Company (Grupo Mexico) common shares
Activity in treasury stock
Balance at beginning of period	(2,194.1)	(2,766.6)	(2,337.3)	(2,766.7)
Dividends paid in common stock	(195.6)	(199.5)	(338.8)	(199.5)
Used for corporate purposes	(0.1)	(0.2)	(0.2)	(0.2)
Balance at end of period	(1,998.4)	(2,567.0)	(1,998.4)	(2,567.0)
Treasury Stock | Parent Company (Grupo Mexico)
Activity in treasury stock
Balance at beginning of period	(360.1)	(390.6)	(363.4)	(382.3)
Other activity, including dividend, interest and foreign currency translation effect	13.5	(11.3)	10.2	(3.1)
Balance at end of period	$ (373.5)	$ (379.3)	$ (373.5)	$ (379.3)