Derivative Instruments - Effect of Derivative Instruments on Statement of Financial Position (Details) - USD ($) $ in Millions	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2019	Jun. 02, 2019	Sep. 30, 2020
Derivative [Line Items]
Interest expense	$ 4.9	$ 9.5	$ 17.5	$ 20.2	$ 16.6
Interest Expense | Interest Rate Swap
Derivative [Line Items]
Interest rate swap agreements designated as cash flow hedges	1.2	0.0	0.0	0.0	1.6
Interest rate swap agreements not designated as cash flow hedges	$ 0.0	$ 1.0	$ 6.4	$ 0.0	$ 0.0