Leases - Schedule of Lease Assets and Lease Liabilities and their Balance Sheet Location (Details) $ in Millions	Sep. 30, 2019 USD ($)
Lease assets:
Operating lease right-of-use assets	$ 307
Finance lease assets	$ 59
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet
Total lease assets	$ 366
Current:
Operating lease liabilities	$ 73
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent
Finance lease liabilities	$ 5
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:DebtCurrent
Total current lease liabilities	$ 78
Non-current:
Operating lease liabilities	254
Finance lease liabilities	$ 54
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtNoncurrent
Total non-current lease liabilities	$ 308
Total lease liabilities	$ 386