INVESTMENTS - Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Digital Cinema Media Ltd. ("DCM")
Related Party Transactions
Loan receivable from related party	$ 0.7		$ 0.7		$ 0.6
Digital Cinema Media Ltd. ("DCM") \| On-screen advertising revenue
Related Party Transactions
Amounts due from related parties	1.8		1.8		3.9
AC JV \| Fathom Events programming
Related Party Transactions
Amount due to related parties	(0.8)		(0.8)		(1.5)
Vasteras Biografer
Related Party Transactions
Loan receivable from related party	1.0		1.0		0.8
Amount due to related parties	(0.7)		(0.7)		(0.6)
CAPA Kinoreklame AS ("CAPA") \| On-screen advertising revenue
Related Party Transactions
Amounts due from related parties					1.4
U.S. theatres and IMAX screen \| Theatre partnerships
Related Party Transactions
Amount due to related parties	(0.7)		(0.7)		$ (0.7)
Other revenues \| Digital Cinema Media Ltd. ("DCM")
Related Party Transactions
Screen advertising revenues	4.1	$ 3.3	8.1	$ 6.6
Other revenues \| Screenvision
Related Party Transactions
Screen advertising revenues	2.0	1.6	3.1	2.9
Operating expense \| Digital Cinema Distribution Coalition, LLC ("DCDC")
Related Party Transactions
Content delivery services	0.3	0.3	0.6	0.6
Film exhibition costs \| AC JV
Related Party Transactions
Gross exhibition cost	$ 5.8	$ 5.7	$ 9.3	$ 12.9