Leases - Supplemental Balance Sheet Information - Operating Leases (Details) $ in Millions |
Sep. 30, 2019
USD ($)
|
|---|---|
| Lessee, Lease, Description [Line Items] | |
| Operating lease right-of-use assets | $ 1,538 |
| Operating lease liability, current | 197 |
| Operating lease liabilities, non-current | 1,459 |
| Total operating lease liabilities | 1,656 |
| Operating Lease Excluding Finance Obligation | |
| Lessee, Lease, Description [Line Items] | |
| Operating lease right-of-use assets | 1,538 |
| Operating lease liability, current | 197 |
| Operating lease liabilities, non-current | 1,459 |
| Total operating lease liabilities | $ 1,656 |