Commercial Commitments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Commercial Commitments
Total commercial commitments (a)	$ 133.3	$ 134.0
Affiliate guarantees [Member]
Commercial Commitments
Total commercial commitments (a)	42.0	42.0
Asset residual value guarantees [Member]
Commercial Commitments
Total commercial commitments (a)	35.0	33.9
Lease payment guarantees [Member]
Commercial Commitments
Total commercial commitments (a)	45.4	47.0
Performance Bonds [Member]
Commercial Commitments
Total commercial commitments (a)	1.3	1.3
Standby letters of credit [Member]
Commercial Commitments
Total commercial commitments (a)	$ 9.6	$ 9.8

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant