CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 108.1	$ 97.2
Other comprehensive income (loss):
Reclassification adjustment transferred to Net income from cash flow hedges	0.3	0.6
Pension and other postretirement benefit costs, net of tax	0.5	0.3
Total Comprehensive Income	$ 108.9	$ 98.1