Stock-Based Compensation Plans - Restricted Stock Units (Details) (USD $)
12 Months Ended
Sep. 30, 2012
Feb. 03, 2012
Sep. 30, 2011
Cash Settled [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number 31,735 44,429 19,000
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price $ 18.10   $ 57.45
Weighted-average exercise price of shares reserved for issuance under non-option equity instrument agreements awarded that validly exist and are outstanding, including vested instruments. $ 18.10    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Granted, Weighted Average Exercise Price $ 0.00    
Share-Based Compensation Arrangement By Share-Based award other than options exercised during the period 0    
Share-Based Compensation Arrangement other than Options forfeited during the period 12,694    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Forfeitures In Period, Weighted Average Exercise Price $ 18.10    
Share-Based Compensation Arrangement By Share-Based Payment Award, Stock Appreciation Rights, Expirations In Period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Expirations In Period, Weighted Average Exercise Price $ 0.00    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Number 30,497    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Weighted Average Exercise Price $ 18.10    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Number 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Weighted Average Exercise Price $ 0    
Stock Settled [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number 356,243 311,014 162,500
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price $ 21.39   $ 59.41
Weighted-average exercise price of shares reserved for issuance under non-option equity instrument agreements awarded that validly exist and are outstanding, including vested instruments. $ 18.94    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 70,000    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Granted, Weighted Average Exercise Price $ 31.50    
Share-Based Compensation Arrangement By Share-Based award other than options exercised during the period 7,845    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Exercises In Period, Weighted Average Exercise Price $ 20.82    
Share-Based Compensation Arrangement other than Options forfeited during the period 16,926    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Forfeitures In Period, Weighted Average Exercise Price $ 18.50    
Share-Based Compensation Arrangement By Share-Based Payment Award, Stock Appreciation Rights, Expirations In Period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Expirations In Period, Weighted Average Exercise Price $ 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Number 353,527    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Weighted Average Exercise Price $ 21.41    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Number 97,938    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Weighted Average Exercise Price $ 19.78    
Cash Settled [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number 76,750   0
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price $ 31.34    
Weighted-average exercise price of shares reserved for issuance under non-option equity instrument agreements awarded that validly exist and are outstanding, including vested instruments. $ 0    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 76,750    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Granted, Weighted Average Exercise Price $ 31.34    
Share-Based Compensation Arrangement By Share-Based award other than options exercised during the period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Exercises In Period, Weighted Average Exercise Price $ 0    
Share-Based Compensation Arrangement other than Options forfeited during the period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Forfeitures In Period, Weighted Average Exercise Price $ 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Stock Appreciation Rights, Expirations In Period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Expirations In Period, Weighted Average Exercise Price $ 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Number 73,947    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Weighted Average Exercise Price $ 31.34    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Number 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Weighted Average Exercise Price $ 0    
Stock Settled [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number 362,500   0
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Weighted Average Exercise Price $ 31.25    
Weighted-average exercise price of shares reserved for issuance under non-option equity instrument agreements awarded that validly exist and are outstanding, including vested instruments. $ 0    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 362,500    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Granted, Weighted Average Exercise Price $ 31.25    
Share-Based Compensation Arrangement By Share-Based award other than options exercised during the period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Exercises In Period, Weighted Average Exercise Price $ 0.00    
Share-Based Compensation Arrangement other than Options forfeited during the period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Forfeitures In Period, Weighted Average Exercise Price $ 0.00    
Share-Based Compensation Arrangement By Share-Based Payment Award, Stock Appreciation Rights, Expirations In Period 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Expirations In Period, Weighted Average Exercise Price $ 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Number 362,500    
Share-Based Compensation Arrangement By Share-Based Payment Award, Vested And Expected To Vest, Outstanding, Weighted Average Exercise Price $ 31.25    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Number 0    
Share-Based Compensation Arrangement By Share-Based Payment Award, Exercisable, Weighted Average Exercise Price $ 0.00