CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Parenthetical (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 2.4	$ 1.7	$ 1.4
Net gain (loss) arising during the period	7.8	(5.6)	(6.7)
Amortization of prior service cost	0	0.2	0.2
Settlement cost	1.9	0	0
Postretirement plans:
Amortization of deferred net loss	1.3	(1.1)	(1.6)
Net loss arising during the period	4.4	(1.1)	(3.1)
Amortization of deferred net transition obligation	0	0.1	0.1
Amortization of prior service cost	(1.1)	(1.0)	(1.6)
Prior service credit arising during the period	0	0	9.5
Deferred commodity contracts hedging (gains) losses reclassified in net income	0.4	(1.6)	12.6
Deferred commodity contracts hedging gains (losses)	0	0.1	(1.7)
Amortization of deferred interest rate swap hedging losses	$ 0.1	$ 0.2	$ 0.2