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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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STOCKHOLDERS' EQUITY - Stock-based compensation (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Feb. 23, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Stock Based Compensation Expense
Stock-based compensation expense		$ 7.2	$ (3.6)	$ 40.9	$ 22.3
Total estimated unrecognized compensation cost related to nonvested stock-based compensation arrangements		20.1		$ 20.1
Weighted average period recognized				1 year 1 month 6 days
Board of director stock award expense
Stock Based Compensation Expense
Stock-based compensation expense				$ 0.9	0.8
Equity Classified Awards
Stock Based Compensation Expense
Stock-based compensation expense		7.3	(3.6)	40.6	22.3
Special awards expense
Stock Based Compensation Expense
Stock-based compensation expense				20.2
Performance stock unit expense
Stock Based Compensation Expense
Stock-based compensation expense		3.6	(7.1)	9.0	11.7
Restricted stock unit expense
Stock Based Compensation Expense
Stock-based compensation expense		3.7	$ 3.5	10.5	$ 9.8
Liability classified awards
Stock Based Compensation Expense
Stock-based compensation expense		(0.1)		0.3
Restricted and performance stock unit expense
Stock Based Compensation Expense
Stock-based compensation expense		$ (0.1)		$ 0.3
Class A common stock \| Special awards expense
Stock Based Compensation Expense
Stock-based compensation expense	$ 14.9
AMC Preferred Equity Units \| Special awards expense
Stock Based Compensation Expense
Stock-based compensation expense	$ 5.3