CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net income	$ 71.5	$ 87.5	$ 96.7	$ 130.7
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss, net of tax of $0.4, $0.6, $0.8 and $1.4, respectively	0.7	0.8	1.5	1.2
Settlement cost, net of tax of $3.2, $0, $3.2 and $0, respectively	5.0	0.0	5.0	0.0
Postretirement Benefit Plans:
Amortization of deferred net loss, net of tax of $0, $0.2, $0 and $0.4, respectively	0.0	0.4	0.0	0.6
Amortization of prior service cost, net of tax of ($0.3), ($0.2), ($0.5) and ($0.5), respectively	(0.4)	(0.5)	(0.8)	(0.9)
Other comprehensive income, net of tax	5.3	0.7	5.7	0.9
Comprehensive income	$ 76.8	$ 88.2	$ 102.4	$ 131.6