Consolidated Statements Of Stockholders Equity (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Changes in defined benefit pension and other post-retirement benefit plans, tax benefit	$ (0.1)	$ 2.1	$ 1.5	$ 0.7

Tax effect, net of reclassification adjustments, of pension and other postretirement benefit plans (gain) loss included in accumulated other comprehensive income (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e640-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (i-k)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration