Stockholders' Equity (Details 5) (USD $)	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Intrinsic value and weighted average remaining contractual life in years of outstanding and exercisable options
Stock price (in dollars per share)	$ 33.50
Options
Fair value assumptions
Expected volatility (as a percent)		60.40%
Volatility rate, minimum (as a percent)	51.80%		63.90%
Volatility rate, maximum (as a percent)	60.60%		64.80%
Risk-free interest rate (as a percent)		0.60%
Risk free interest rate, minimum (as a percent)	0.10%		0.30%
Risk free interest rate, maximum (as a percent)	1.00%		1.70%
Expected forfeiture rate (as a percent)	19.70%	19.00%	18.40%
Intrinsic value and weighted average remaining contractual life in years of outstanding and exercisable options
Intrinsic value of outstanding shares	$ 28,265,000
Intrinsic value of exercisable options	23,603,000
Weighted average grant date fair value of options granted (in dollars per share)	$ 35.76	$ 34.42	$ 15.21
Intrinsic value of options exercised	$ 4,943,000	$ 50,899,000	$ 43,706,000

Represents the forfeiture rate that is used in valuing an option.

No definition available.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(iv)

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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- Definition

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.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

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