Share-Based Compensation (Market-Based Deferred Stock Units Valuation Assumptions) (Details) (Market-Based Deferred Stock Units [Member])
6 Months Ended
Mar. 31, 2015
Market-Based Deferred Stock Units [Member]
 
Share-based Compensation Arrangement by Share-based Award [Line Items]  
Expected volatility 19.60%
Risk-free interest rate 0.90%
Expected dividend yield 2.50%