CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - 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	$ 32.0	$ 42.5	$ 175.6	$ 226.3
Other comprehensive income:
Reclassification adjustment transferred to Net income from cash flow hedges	0.2	0.3	0.6	0.7
Pension and other postretirement benefit costs, net of tax	0.9	0.5	2.3	2.9
Total Comprehensive Income	$ 33.1	$ 43.3	$ 178.5	$ 229.9