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