Fair Value Measurements (Details Textuals) (USD $) In Millions, unless otherwise specified	Jun. 30, 2011	Sep. 30, 2010
Fair Value Measurements (Textuals) [Abstract]
Aggregate fair value of senior and convertible senior notes	$ 1,956.2	$ 2,244.0
Aggregate carrying value of senior and convertible senior notes	1,758.3	2,050.1
Interest rate of convertible senior notes	2.00%
Aggregate fair value of convertible senior notes	556.6	553.8
Carrying value of the equity component of convertible senior notes	136.7	136.7
Aggregate carrying value of convertible senior notes	$ 411.3	$ 391.9

Fair value measurements.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. Fair value of convertible debt at the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Convertible Security
-URI http://asc.fasb.org/extlink&oid=6509036

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

+ References

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- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

+ References

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- Definition

Interest rate stated in the contractual debt agreement.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents notes payable as of the balance sheet date.

+ References

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-Paragraph 2, 4
-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.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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