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Revenues - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2025
Sep. 30, 2024
Dec. 31, 2024
Revenue From Contract With Customer [Line Items]          
Current deferred revenues $ 229.0   $ 229.0   $ 190.5
Revenue recognized     162.7    
Cancelled event liabilities 1.0   1.0   1.2
Provision for expected credit losses 0.5   1.4 $ 0.5  
Accounts receivable write off 0.6   $ 1.0    
Maximum [Member]          
Revenue From Contract With Customer [Line Items]          
Payment term     60 days    
Minimum [Member]          
Revenue From Contract With Customer [Line Items]          
Payment term     30 days    
Other Noncurrent Liabilities [Member]          
Revenue From Contract With Customer [Line Items]          
Long-term deferred revenues $ 0.4   $ 0.4    
Trade Show and Other Events [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]          
Revenue From Contract With Customer [Line Items]          
Concentration risk, percentage 87.10% 86.00% 91.10% 89.30%  
Trade Shows [Member] | COVID-19 [Member]          
Revenue From Contract With Customer [Line Items]          
Current deferred revenues $ 0.8   $ 0.8    
Accounts receivable credits reclassified to cancelled event liabilities $ 0.2   $ 0.2   $ 1.1