Supplemental Financial Data - Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 07, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 14.1	$ 7.3	$ 14.1	$ 24.2
Additions charged to costs and expenses	0.7	7.8	5.2	6.7
Write-offs	(0.6)	(5.7)		(9.1)
Recoveries	0.2	1.7	2.3	2.7
Other	0.2	(0.1)	(0.2)	(10.4)
Balance at end of period	$ 14.6	$ 11.0	$ 7.3	$ 14.1