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Summary of Significant Accounting Policies, Contract Liabilities - Customer Loyalty Programs (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Contract Liabilities - Customer Loyalty Programs [Abstract]      
Contract liabilities for customer loyalty programs $ 18.2 $ 12.5  
Contract liabilities impact to revenue $ 5.7 $ 1.3 $ 1.1