Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | |
|---|---|---|---|
Dec. 31, 2016 |
Mar. 31, 2017 |
Mar. 31, 2016 |
|
| Defined Benefit Plan Disclosure | |||
| Pension Contributions | $ 63 | $ 63 | |
| U S Qualified Pension Plan [Member] | |||
| Defined Benefit Plan Disclosure | |||
| Pension Contributions | $ 55 | ||
| Non-US Plans and US Non Qualified Plans | |||
| Defined Benefit Plan Disclosure | |||
| Pension Contributions | 8 | ||
| Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year | $ 13 | ||