STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Comprehensive income:
Net income	$ 42.7	$ 54.1
Derivative instruments:
Reclassification of loss to net income, net of tax of $0	0.0	0.0
Total other comprehensive income	0.0	0.0
Total comprehensive income	$ 42.7	$ 54.1