Derivative and Financial Instruments - Cost Basis to Fair Value (Details) $ in Millions |
Mar. 31, 2020
USD ($)
|
|---|---|
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost Basis | $ 462 |
| Fair Value | 459 |
| Corporate Bonds [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost Basis | 269 |
| Fair Value | 266 |
| Commercial Paper [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost Basis | 129 |
| Fair Value | 129 |
| U.S. Government Obligations [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost Basis | 21 |
| Fair Value | 21 |
| U.S. Government Agency Obligations [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost Basis | 5 |
| Fair Value | 5 |
| Asset-backed Securities [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost Basis | 38 |
| Fair Value | $ 38 |