CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Parenthetical - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 0.3	$ 0.3	$ 1.7	$ 0.9
Settlement cost	2.4	0.0	2.4	0.0
Postretirement Benefit Plans:
Amortization of deferred net loss	0.2	0.1	0.6	0.4
Amortization of prior service cost	(0.3)	(0.2)	(0.8)	(0.8)
Amortization of deferred interest rate swap hedging losses	$ 0.0	$ 0.0	$ 0.0	$ 0.1