CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Comprehensive income:
Net income	$ 128.7	$ 138.8
Derivative instruments:
Reclassification of loss to net income, net of tax of $0.1	0.3	0.3
Total other comprehensive income	0.3	0.3
Total comprehensive income	$ 129.0	$ 139.1