LEASES - Lease costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lessee, Lease, Description [Line Items]
Interest on lease liabilities	$ 1.6	$ 2.1
Total lease cost	255.7	263.9
Depreciation and amortization
Lessee, Lease, Description [Line Items]
Amortization of finance lease assets	1.9	2.7
Finance lease obligations
Lessee, Lease, Description [Line Items]
Interest on lease liabilities	1.6	2.1
Theatres | Rent
Lessee, Lease, Description [Line Items]
Operating lease cost	216.9	218.9
Variable lease cost	20.9	23.0
Theatres | Operating expense
Lessee, Lease, Description [Line Items]
Operating lease cost	2.2	1.7
Equipment | Operating expense
Lessee, Lease, Description [Line Items]
Operating lease cost	3.9	3.5
Variable lease cost	7.0	10.7
Office And Other | General and administrative: other
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 1.3	$ 1.3