Segments - Holdings - Reconciliation of Net Income (Loss) to Adjusted EBITDA (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Net income (loss)		$ 91.2	$ (23.9)	$ 209.1	$ (169.2)
Add (deduct):
Income tax expense (benefit)		21.4	3.4	29.8	6.3
Interest expense	[1]	38.1	38.4	112.0	114.6
Other (income) expense, net	[2]	(4.9)	4.5	(18.9)	19.2
Cash distributions from equity investees	[3]	1.6	0.0	3.2	1.5
Depreciation and amortization		51.9	58.3	159.6	181.0
Impairment of long-lived and other assets		2.0	15.2	12.1	107.5
Restructuring costs		0.0	0.0	0.0	(0.2)
Gain on disposal of assets and other		(6.1)	(1.2)	(8.8)	(6.4)
Loss on debt extinguishment and refinancing		0.0	0.0	10.7	0.0
Non-cash rent expense		(4.8)	(2.8)	(13.2)	(7.5)
Share based awards compensation expense		6.4	5.2	18.9	16.2
Adjusted EBITDA		$ 196.8	$ 99.5	$ 514.5	$ 263.0

[1] Includes amortization of debt issuance costs, amortization of original issue discount, and amortization of accumulated (gains) losses for amended swap agreements.

[2] Includes interest income, foreign currency exchange and other related losses, interest expense - NCM, equity in income (loss) of affiliates and unrealized gain on investment in NCMI.

[3] Reflects cash distributions received from equity investees that were recorded as a reduction of the respective investment balances. These distributions are reported entirely within the U.S. operating segment.