CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Parenthetical (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 1.2	$ 2.4	$ 1.7
Net gain (loss) arising during the period	(7.0)	7.8	(5.6)
Amortization of prior service cost	0	0	0.2
Settlement (Curtailment) cost	(0.1)	1.9	0
Postretirement plans:
Amortization of deferred net loss	0.5	1.3	(1.1)
Net loss arising during the period	(1.9)	4.4	(1.1)
Amortization of deferred net transition obligation	0	0	0.1
Amortization of prior service cost	(1.1)	(1.1)	(1.0)
Deferred commodity contracts hedging (gains) losses reclassified in net income	0	0.4	(1.6)
Deferred commodity contracts hedging gains (losses)	0	0	0.1
Amortization of deferred interest rate swap hedging losses	$ 0.1	$ 0.1	$ 0.2