Stock Based Compensation (Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Wieghted Average Grant Date Fair Value) (Details) (USD $)	3 Months Ended	6 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of grants	$ 4.27	$ 4.79	$ 4.31	$ 4.49
Expected term in years	4 years 5 months 12 days	4 years 4 months 13 days	4 years 5 months 12 days	4 years 4 months 13 days
Estimated volatility	58.00%	60.00%	59.00%	60.00%
Risk-free interest rate	0.61%	0.61%	0.53%	0.68%
Dividend yield	0.00%	0.00%	0.00%	0.00%
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of grants	$ 2.30	$ 2.98	$ 2.30	$ 2.98
Expected term in years	5 months 27 days	6 months	5 months 27 days	6 months
Estimated volatility	32.00%	52.00%	32.00%	52.00%
Risk-free interest rate	0.11%	0.07%	0.11%	0.07%
Dividend yield	0.00%	0.00%	0.00%	0.00%

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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.

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