MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 3.3	$ 20.0
Equity securities, FV-NI, realized gain	1.1
Unrealized losses recorded in other income		9.7
Unrealized gains recorded in other income			$ 4.4
Unrealized Gains/(Losses) on Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Losses recorded on securities intended to be sold	1.2
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Equity securities	173.6	170.1
Marketable securities held in nuclear decommissioning trusts	$ 164.3	$ 163.2