Share-Based Compensation (Summary of Stock Option Activity) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
Mar. 31, 2013	Sep. 30, 2012
Number of Options:
Outstanding at October 1, 2012	1,450
Granted	0
Exercised	(188)
Forfeited	(17)
Outstanding at March 31, 2013	1,245	1,450
Exercisable at March 31, 2013	875
Wtd. Avg. Exercise Price (in dollars per share):
Outstanding at October 1, 2012	$ 29.74
Granted	$ 0.00
Exercised	$ 19.17
Forfeited	$ 39.26
Outstanding at March 31, 2013	$ 31.16	$ 29.74
Exercisable at March 31, 2013	$ 27.56
Wtd. Avg. Remaining Contractual Life (Years), Outstanding at October 1, 2012	6 years	6 years 1 month 6 days
Wtd. Avg. Remaining Contractual Life (Years), Outstanding at December 31, 2012	6 years	6 years 1 month 6 days
Wtd. Avg. Remaining Contractual Life (Years), Exercisable at December 31, 2012	5 years
Aggregate Intrinsic Value, Outstanding at October 1, 2012	$ 22,663
Aggregate Intrinsic Value, Exercised	6,076
Aggregate Intrinsic Value, Outstanding at December 31, 2012	26,609	22,663
Aggregate Intrinsic Value, Exercisable at December 31, 2012	$ 21,860

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Net number of share options (or share units) granted during the period.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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