Fair Value Measures (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - Recurring - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Other assets, non-current | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 1	$ 1
Foreign currency forward contracts | Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure	0	1
Quoted prices in active markets for identical instruments (Level 1) | Other assets, non-current | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	1	1
Quoted prices in active markets for identical instruments (Level 1) | Foreign currency forward contracts | Other current liabilities | Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure	0	0
Significant other observable inputs (Level 2) | Other assets, non-current | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Significant other observable inputs (Level 2) | Foreign currency forward contracts | Other current liabilities | Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure	0	1
Fair Value, Inputs, Level 3 [Member] | Other assets, non-current | Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign currency forward contracts | Other current liabilities | Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure	$ 0	$ 0