MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	$ 3.1		$ 3.1		$ 20.0
Unrealized (loss) gain recorded in other income	4.7	$ 4.7	3.9	$ 9.1
Losses recorded on securities intended to be sold			7.2	3.2
Unrealized Gains/(Losses) on Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Losses recorded on securities intended to be sold			1.2	$ 0.0
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	161.6		161.6		170.1
Marketable securities held in nuclear decommissioning trust	$ 165.8		$ 165.8		$ 163.2