Commitments and Contingencies - Guarantor Obligations (Details) $ in Millions	Dec. 31, 2018 USD ($)
Guarantor Obligations [Line Items]
Fiscal 2019	$ 145
Fiscal 2020	485
Fiscal 2021 and Thereafter	522
Total	1,152
Surety bonds
Guarantor Obligations [Line Items]
Fiscal 2019	20
Fiscal 2020	334
Fiscal 2021 and Thereafter	101
Total	455
Letters of credit
Guarantor Obligations [Line Items]
Fiscal 2019	102
Fiscal 2020	106
Fiscal 2021 and Thereafter	327
Total	535
Stand-by letters of credit
Guarantor Obligations [Line Items]
Fiscal 2019	23
Fiscal 2020	45
Fiscal 2021 and Thereafter	94
Total	$ 162