Revenue Recognition - Changes in Advances and Deferred Revenues (Detail) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2025	Dec. 31, 2024
NCM
Change in Contract with Customer Liability [Line Items]
Amounts recognized as accounts receivable		$ 2.2	$ 2.1
Other Deferred Revenues
Change in Contract with Customer Liability [Line Items]
Balance at January 1, 2025	[1]	250.8
Amounts recognized as accounts receivable	[1]	1.6
Cash received from customers in advance	[1]	177.3
Interest accrued related to significant financing component	[1]	0.0
Revenue recognized during period	[1]	(183.7)
Foreign currency translation adjustments	[1]	0.7
Balance at June 30, 2025	[1]	246.7	250.8
N C M Screen Advertising Advances
Change in Contract with Customer Liability [Line Items]
Balance at January 1, 2025		318.5
Amounts recognized as accounts receivable		0.0
Cash received from customers in advance		0.0
Interest accrued related to significant financing component	[1]	10.7
Revenue recognized during period		(16.3)
Foreign currency translation adjustments		0.0
Balance at June 30, 2025		$ 312.9	$ 318.5

[1] Includes liabilities associated with outstanding gift cards and discount ticket vouchers, points, credits or rebates outstanding under the Company’s loyalty and subscription programs and revenue collected in advance for screen advertising and other promotional activities. Amounts are classified as accounts payable and accrued expenses or other long-term liabilities on the condensed consolidated balance sheet.