Commitments and Contingencies - Guarantor Obligations (Details) $ in Millions	Sep. 30, 2017 USD ($)
Guarantor Obligations [Line Items]
Fiscal 2018	$ 220
Fiscal 2019	249
Fiscal 2020 and Thereafter	386
Total	855
Surety bonds
Guarantor Obligations [Line Items]
Fiscal 2018	47
Fiscal 2019	186
Fiscal 2020 and Thereafter	35
Total	268
Performance letters of credit
Guarantor Obligations [Line Items]
Fiscal 2018	161
Fiscal 2019	57
Fiscal 2020 and Thereafter	317
Total	535
Stand-by letters of credit
Guarantor Obligations [Line Items]
Fiscal 2018	12
Fiscal 2019	6
Fiscal 2020 and Thereafter	34
Total	$ 52