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
Net income	$ 100.2	$ 110.7	$ 147.3	$ 165.7
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss, net of tax of $0.3, $0.3, $0.5 and $0.5, respectively	1.0	1.0	1.7	1.7
Settlement cost, net of tax of $0.1, $0.0, $2.3 and $0.0, respectively	0.5	0.0	7.1	0.0
Postretirement Benefit Plans:
Amortization of prior service credit, net of tax of ($0.1), ($0.2), ($0.2) and ($0.3), respectively	(0.4)	(0.3)	(0.9)	(0.8)
Amortization of deferred net gain, net of tax of $0.0, $0.0, $0.0 and $0.0, respectively	0.1	0.0	0.1	0.0
Other comprehensive income, net of tax	1.0	0.7	7.8	0.9
Comprehensive income	$ 101.2	$ 111.4	$ 155.1	$ 166.6