Income Taxes (Narrative) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Mar. 31, 2016 |
Mar. 31, 2015 |
Mar. 31, 2016 |
Mar. 31, 2015 |
Sep. 30, 2015 |
|
| Income Taxes | |||||
| Effective Income Tax Rate, Continuing Operations | 26.80% | 32.40% | 22.20% | 27.70% | |
| Statute of Limitations, Range, Minimum (in years) | 3 years | ||||
| Statute of Limitations, Range, Maximum (in years) | 5 years | ||||
| Income Taxes Paid | $ 31 | $ 78 | |||
| Unrecognized Tax Benefits | $ 47 | 47 | $ 39 | ||
| Unrecognized tax benefits that, if recognized, would impact the effective income tax rate | 16 | 16 | 11 | ||
| Accrued Income tax penalties and interest | 2 | 2 | $ 1 | ||
| Interest and penalties expense (income) | 0 | $ 0 | |||
| Minimum [Member] | |||||
| Income Taxes | |||||
| Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit | 0 | 0 | |||
| Maximum [Member] | |||||
| Income Taxes | |||||
| Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit | $ 13 | $ 13 | |||