Summary of Significant Accounting Policies, Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Contract Liabilities - Customer Loyalty Programs [Abstract]
Contract liabilities for customer loyalty programs	$ 24.5		$ 24.5		$ 18.2
Contract liabilities impact to revenue	$ (0.7)	$ (1.8)	$ (6.3)	$ (5.3)