Summary of Significant Accounting Policies, Revenue Recognition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition [Abstract]
Sales returns	$ 49.5	$ 52.2	$ 52.0
Allowance for Product Returns [Member]
Revenue Recognition [Abstract]
Accrued reserve	$ 4.0	$ 3.9