Commitments and Contingencies - Contractual Commitments and Contingencies (Details) $ in Millions |
3 Months Ended |
|---|---|
|
Mar. 31, 2018
USD ($)
| |
| Commitments and Contingencies Disclosure [Abstract] | |
| Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees | $ 879 |