Significant Accounting Policies - Schedule Of Allowance For Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance balance, beginning of year	$ 1.4	$ 1.2	$ 1.7
Provision	0.9	1.2	0.2
Write offs	(0.6)	(1.0)	(0.7)
Allowance balance, end of year	$ 1.7	$ 1.4	$ 1.2