Earnings Per Share (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Numerator:
Net income	$ 40.6	$ 27.8	$ 68.3	$ 7.4
Denominator:
Denominator for basic earnings per share - weighted average common shares	317.6	319.3	317.0	319.2
Effect of dilutive securities:
Employee stock awards	2.5	0.6	1.3	0.3
Denominator for diluted earnings per share - adjusted weighted average common shares	320.1	319.9	318.3	319.5
Earnings (Loss) Per Share (Textual) [Abstract]
Number of shares excluded from computation of earnings per share	8.7	9.5	8.7	9.5

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Antidilution

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Glossary Diluted Earnings Per Share

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+ Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

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-Glossary Weighted-Average Number of Common Shares Outstanding

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+ Details