CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 75.7	$ 42.2	$ 183.8	$ 139.4
Other comprehensive income:
Reclassification adjustment transferred to Net income from cash flow hedges	0.1	0.2	0.4	0.8
Pension and other postretirement benefit costs, net of tax	1.9	1.2	2.4	1.5
Total Comprehensive Income	$ 77.7	$ 43.6	$ 186.6	$ 141.7