SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Valuation and qualifying accounts
Balance at beginning of period	$ 18.3	$ 4.2	$ 4.2
Expense	6.2	8.2	5.5
Deferral	(7.0)	9.7	0.0
Net write-offs	(6.4)	(3.8)	(5.5)
Balance at end of period	$ 11.1	$ 18.3	$ 4.2