Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 66.9	$ 69.2	$ 325.1	$ 107.2
Interest rate swap:
Realized gain (loss)	(0.4)	0.0	(0.5)	0.0
Unrealized gain (loss)	0.5	0.0	(3.7)	0.0
Reclassified to interest expense	0.4	0.0	0.5	0.0
Total	0.5	0.0	(3.7)	0.0
Deferred income tax (benefit) expense	0.1	0.0	(0.9)	0.0
Other comprehensive income (loss)	0.4	0.0	(2.8)	0.0
Comprehensive income	$ 67.3	$ 69.2	$ 322.3	$ 107.2