Summary of Impairment Charges (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Impaired Long-Lived Assets Held and Used [Line Items]
Total Impairment		$ 9.4	$ 92.3	$ 10.1	$ 92.3
U.S. Operating Segment
Impaired Long-Lived Assets Held and Used [Line Items]
Theatre properties		3.9	2.5	3.9	2.5
Theatre operating lease right-of-use assets		3.4	2.0	3.4	2.0
Total Impairment		7.3	91.3	8.0	91.3
U.S. Operating Segment | Investment In NCM
Impaired Long-Lived Assets Held and Used [Line Items]
Investment in NCM	[1]	0.0	86.8	0.7	86.8
International Operating Segment
Impaired Long-Lived Assets Held and Used [Line Items]
Theatre properties		0.6	0.7	0.6	0.7
Theatre operating lease right-of-use assets		1.5	0.3	1.5	0.3
Total Impairment		$ 2.1	$ 1.0	$ 2.1	$ 1.0

[1] See discussion at Impairment of NCMI Investment in Note 8.