CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Comprehensive income:
Net income	$ 108.1	$ 101.5	$ 236.8	$ 240.3
Derivative instruments:
Reclassification of loss to net income, net of tax of $0.1, $0.1, $0.2, and $0.2, respectively	0.3	0.3	0.6	0.6
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	0.1	0.1	0.2	0.2
Total other comprehensive income	0.3	0.3	0.6	0.6
Total comprehensive income	$ 108.4	$ 101.8	$ 237.4	$ 240.9