MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	$ 26.4		$ 26.4		$ 40.2
Unrealized (loss) gain recorded in other income	(4.7)	$ 1.9	(9.1)	$ 3.0
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	182.4		182.4		214.0
Marketable securities held in nuclear decommissioning trust	$ 174.4		$ 174.4		$ 189.9

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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