Fair Value Measurements (Fair Value of Financial Assets and Liabilities Measured on a Recurring Basis) (Details) - USD ($)
$ in Millions
6 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Sep. 30, 2015
Fair Value of Assets and Liabilities Measured on Recurring Basis      
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount $ 0 $ 0  
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount 0 0  
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount 0 0  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 0 0  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 0 0  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3 0 $ 0  
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Deferred Compensation Plan Investments [Member]      
Fair Value of Assets and Liabilities Measured on Recurring Basis      
Assets at fair value 51   $ 50
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Exchange Forward [Member]      
Fair Value of Assets and Liabilities Measured on Recurring Basis      
Liabilities at fair value (8)   (11)
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Swap Assets [Member]      
Fair Value of Assets and Liabilities Measured on Recurring Basis      
Assets at fair value 37   34
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Exchange Forward [Member]      
Fair Value of Assets and Liabilities Measured on Recurring Basis      
Assets at fair value 9   7
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Contingent Consideration [Member]      
Fair Value of Assets and Liabilities Measured on Recurring Basis      
Liabilities at fair value $ (12)   $ (12)