Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (119.1)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(8.0)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2.1
Other Comprehensive Income (Loss), Net of Tax	(5.9)
Ending Accumulated Other Comprehensive Income (Loss), Net of Tax	(125.0)
Cash flow hedge before reclassification	0.5
Cash flow hedge reclassification, net of tax	(0.1)
Cash Flow Hedge Period OCI	0.4
Cash Flow Hedge AOCI Balance, Net Of Tax	(0.1)		(0.5)
Pension before reclassification	0
Pension OPEB Reclassification, Net of Tax	2.2
Pension OPEB Period OCI	2.2
Pension OPEB AOCI Balance, Net Of Tax	(127.9)		(130.1)
Available For Sale OCI Before Reclassification	0
Available For Sale Reclassification, Net of Tax	0
Available For Sale Period OCI	0
Available For Sale AOCI Balance, Net Of Tax	0.7		0.7
CTA Before Reclassification	(8.5)
CTA Period OCI	(8.5)
CTA AOCI Balance, Net Of Tax	2.3		10.8
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Cost of good sold	(503.8)	(489.7)
Interest expense, net	(7.3)	(7.2)
Other (expense) income, net	0.8	0.1
Income before income taxes	91.2	94.6
Provision for income taxes	(24.4)	(31.0)
Net income	66.8	63.6
Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges [Member]
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Cost of good sold	0.1
Income before income taxes	0.1
Provision for income taxes	0
Net income	0.1
Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Pension Gain Loss Amort Before Tax	(3.6)
Pension Service Cost Amort Before Tax	0.2
Income before income taxes	(3.4)
Provision for income taxes	1.2
Net income	(2.2)
Reclassification Out Of Accumulated Other Comprehensive Income Member [Member]
Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax [Abstract]
Net income	$ (2.1)