Indebtedness (Fair Value And Carrying Value Of Long-Term Debt) (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Carrying Amount	$ 1,244.0	$ 1,239.6
Estimated Fair Value	1,303.3	1,270.3
Series 2005-1 Notes [Member]
Debt Instrument [Line Items]
Carrying Amount	308.0	296.3
Estimated Fair Value	312.2	310.6
Series 2007-1 Notes [Member]
Debt Instrument [Line Items]
Carrying Amount	300.0	300.0
Estimated Fair Value	327.7	321.3
2010 Senior Notes [Member]
Debt Instrument [Line Items]
Carrying Amount	497.2	497.0
Estimated Fair Value	524.6	492.1
2008 Term Loan [Member]
Debt Instrument [Line Items]
Carrying Amount	138.8	146.3
Estimated Fair Value	$ 138.8	$ 146.3

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant