CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Parenthetical - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 0.4	$ 0.6	$ 0.8	$ 1.4
Settlement cost	3.2	0.0	3.2	0.0
Postretirement Benefit Plans:
Amortization of deferred net loss	0.0	0.2	0.0	0.4
Amortization of prior service cost	(0.3)	(0.2)	(0.5)	(0.5)
Amortization of deferred interest rate swap hedging losses	$ 0.0	$ 0.0	$ 0.0	$ 0.0