CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 297.0	$ 302.2	$ 222.0
Other comprehensive income (loss):
Loss on cash flow hedge	(1.5)	0.0	0.0
Reclassification adjustment transferred to Net income from cash flow hedges	2.5	2.4	2.4
Pension and other postretirement benefit costs	(1.9)	1.8	(13.9)
Total Comprehensive Income	$ 296.1	$ 306.4	$ 210.5