REVENUE RECOGNITION - Transaction price allocated to the remaining performance obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Customer Frequency Program
Deferred revenues and income	$ 408.6	$ 405.4
Gift Card And Ticket Exchange
Customer Frequency Program
Redemption period	24 months
Deferred revenues and income	$ 322.0
Loyalty Program
Customer Frequency Program
Redemption period	24 months
Deferred revenues and income	$ 65.5
Exhibitor Services Agreement
Customer Frequency Program
Expected to be recognized as revenue	510.4
Exhibitor Services Agreement \| Year Ended 2022
Customer Frequency Program
Expected to be recognized as revenue	19.3
Exhibitor Services Agreement \| Year Ended 2023
Customer Frequency Program
Expected to be recognized as revenue	20.8
Exhibitor Services Agreement \| Year Ended 2024
Customer Frequency Program
Expected to be recognized as revenue	22.3
Exhibitor Services Agreement \| Year Ended 2025
Customer Frequency Program
Expected to be recognized as revenue	24.0
Exhibitor Services Agreement \| Year Ended 2026
Customer Frequency Program
Expected to be recognized as revenue	25.8
Exhibitor Services Agreement \| Years Ended 2027 through February 2037
Customer Frequency Program
Expected to be recognized as revenue	$ 398.2