Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2011	Dec. 31, 2010
Marketable and Non-Marketable Securities
Value of non-marketable security accounted for under the cost method	$ 72.4	$ 72.4
Net unrealized gains (losses) recorded in other comprehensive income (loss)	43.5	79.3
Available for sale securities
Marketable and Non-Marketable Securities
Aggregate unrealized gain (loss) on available-for-sale investments, net	41.9	79.0
Available for sale securities \| Securities in captive insurance subsidiary portfolio
Marketable and Non-Marketable Securities
Investment maturity range, minimum (in years)	1
Investment maturity range, maximum (in years)	10
Available for sale securities \| CSCG
Marketable and Non-Marketable Securities
Number of shares owned (in shares)	35.4
Carrying value of investment	180.9	228.4
Available for sale securities \| CAPC
Marketable and Non-Marketable Securities
Number of shares owned (in shares)	35.4
Carrying value of investment	92.8	82.4
Held-to-maturity securities
Marketable and Non-Marketable Securities
Investments used to fund debt service requirements	$ 25.1	$ 25.1

For an unclassified balance sheet, this item represents equity securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 86-40

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

+ Details

- Definition

This element represents the aggregate carrying amount of all cost-method investments held by the Company. Generally, such investments do not have readily determinable fair values and are not required to be accounted for by the equity method. The carrying amount of such securities equates to cost, adjusted for other-than-temporary impairment. The cost method and lower-of-cost or market, an adaptation of the cost method, is generally followed for most investments in noncontrolled corporations, in some corporate joint ventures, and to a lesser extent in unconsolidated subsidiaries, particularly foreign.

+ References

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 5

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 03-1

-Paragraph 22

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 325

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

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+ Details

- Definition

The carrying amount of securities categorized as held-to-maturity which serve as security for borrowings or other arrangements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-Publisher SEC

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-Number 210

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-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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-Publisher FASB

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-Section S99

-Paragraph 1

-Subparagraph (SX210.4-08(b))

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+ Details