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Intangible Assets - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Sep. 30, 2020
Goodwill [Line Items]      
Goodwill $ 2,426,379,000 $ 2,426,379,000 $ 2,400,000,000
Change in goodwill $ 0    
Peter B. Cannell & Co.      
Goodwill [Line Items]      
Goodwill, written off related to sale of business Unit   $ 9,800,000