LEASES - Lease costs (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Leases:
Interest expense on lease liabilities	$ 1.2	$ 0.9
Total lease cost	241.6	247.5
Depreciation and amortization
Leases:
Amortization of finance lease assets	0.7	0.5
Finance lease obligations
Leases:
Interest expense on lease liabilities	0.8	0.9
Theatre \| Rent
Leases:
Operating lease cost	190.2	197.7
Variable lease cost	27.9	26.8
Theatre \| Operating expense
Leases:
Operating lease cost	1.2	0.2
Theatre \| Finance lease obligations
Leases:
Variable lease cost	0.4
Equipment \| Operating expense
Leases:
Operating lease cost	9.7	6.7
Variable lease cost	9.4	13.4
Office and other \| General and administrative: other
Leases:
Operating lease cost	$ 1.3	$ 1.3

Amount of interest expense on finance lease liability.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479589/842-20-55-53

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

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Amount of lease cost recognized by lessee for lease contract.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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