CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Parenthetical - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 0.6	$ 0.3	$ 1.4	$ 0.6
Postretirement Benefit Plans:
Amortization of deferred net loss	0.2	0.2	0.4	0.3
Amortization of prior service cost	(0.2)	(0.3)	(0.5)	(0.6)
Amortization of deferred interest rate swap hedging losses	$ 0.0	$ 0.0	$ 0.0	$ 0.1