LEASES - Lease costs (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Leases:
Interest expense on lease liabilities	$ 1.4	$ 1.7	$ 4.6	$ 4.3
Total lease cost	276.4	261.7	798.9	764.6
Location, Statement of Income, Balance [Axis]: us-gaap:DepreciationDepletionAndAmortization
Leases:
Amortization of finance lease assets	0.9	0.7	2.5	2.1
Location, Statement of Income, Balance [Axis]: us-gaap:FinanceLeaseInterestExpense
Leases:
Interest expense on lease liabilities	0.8	0.8	2.5	2.4
Theatre properties \| Location, Statement of Income, Balance [Axis]: us-gaap:FinanceLeaseInterestExpense
Leases:
Variable operating and finance lease cost	0.6	0.9	2.1	1.9
Theatre properties \| Location, Statement of Income, Balance [Axis]: us-gaap:OperatingLeaseExpense
Leases:
Operating lease cost	186.3	194.0	571.9	577.6
Variable operating and finance lease cost	34.9	30.1	97.2	87.2
Theatre properties \| Location, Statement of Income, Balance [Axis]: us-gaap:OtherCostAndExpenseOperating
Leases:
Operating lease cost	2.8	1.8	5.6	5.2
Equipment \| Location, Statement of Income, Balance [Axis]: us-gaap:OtherCostAndExpenseOperating
Leases:
Operating lease cost	13.4	11.4	38.8	31.5
Variable operating and finance lease cost	35.4	20.8	74.6	52.8
Office and other \| Location, Statement of Income, Balance [Axis]: us-gaap:OtherGeneralAndAdministrativeExpense
Leases:
Operating lease cost	$ 1.3	$ 1.2	$ 3.7	$ 3.9

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
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Publisher FASB
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Period Type:	duration

- Definition

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+ References

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- Definition

Amount of lease cost recognized by lessee for lease contract.

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- Definition

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-Topic 842
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- Definition

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.

+ References

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- Definition

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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