CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income	$ 250.9	$ 205.1	$ 398.2	$ 370.8
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss, net of tax of $0.3, $0.3, $0.8 and $0.8, respectively	0.9	0.8	2.6	2.5
Settlement cost, net of tax of $0.3, $1.1, $2.6 and $1.1, respectively	0.8	3.1	7.9	3.1
Postretirement Benefit Plans:
Amortization of prior service credit, net of tax of ($0.2), ($0.1), ($0.4) and ($0.4), respectively	(0.4)	(0.5)	(1.3)	(1.3)
Amortization of deferred net gain, net of tax of $0.0, $0.0, $0.0 and $0.0, respectively	0.0	0.0	0.1	0.0
Other comprehensive income, net of tax	0.7	3.4	8.5	4.3
Comprehensive income	251.6	208.5	406.7	375.1
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	$ (0.6)	$ 0.0	$ (0.6)	$ 0.0