CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Parenthetical - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 0.4	$ 0.3	$ 1.2	$ 1.7
Settlement cost	0.0	2.4	3.2	2.4
Postretirement Benefit Plans:
Amortization of deferred net loss	0.0	0.2	0.0	0.6
Amortization of prior service cost	(0.2)	(0.3)	(0.7)	(0.8)
Amortization of deferred interest rate swap hedging losses	$ 0.0	$ 0.0	$ 0.0	$ 0.0