Financial Instruments and Fair Value Measurements (Details Textual) (USD $)	3 Months Ended	6 Months Ended	9 Months Ended
Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2011	Sep. 30, 2010
Financial Instruments and Fair Value Measurements (Textuals) [Abstract]
Remaining cash equivalents	$ 846,775,000		$ 846,775,000	$ 938,565,000
Maturity period of cash equivalents at the time of purchase		Three months or less
Maturity period of instruments in short term investments			Three months to one year
Transfer of assets in and out of level 1, 2 and 3 measurements during the period	0		0
Transfer of liabilities in and out of level 1, 2 and 3 measurements during the period	$ 0		$ 0

Financial Instruments and Fair Value Measurements.

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- Definition

The maximum maturity period of liquid investments classified as cash equivalents in the consolidated balance sheet.

+ Details

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- Definition

The maturity period of time deposits classified as short-term investments in the consolidated balance sheet.

+ Details

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- Definition

Amounts of cash equivalents that are carried at cost and are not measured at fair value under the fair value measurement requirements for financial assets and liabilities.

+ Details

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- Definition

This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph c(3)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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- Definition

This element represents [net] transfers in to and out of liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

+ Details

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