Debt - Availability Under Revolving Credit Facilities (Details) $ in Millions |
Dec. 31, 2019
USD ($)
|
|---|---|
| Line of Credit Facility [Line Items] | |
| Availability under revolving credit facilities | $ 3,109 |
| 2018 Unsecured Revolving Credit Facility | |
| Line of Credit Facility [Line Items] | |
| Availability under revolving credit facilities | 2,650 |
| Other revolving credit facilities | |
| Line of Credit Facility [Line Items] | |
| Availability under revolving credit facilities | $ 459 |