Commitments and Contingencies - Additional Information (Details) MMBTU in Millions, $ in Millions |
1 Months Ended | 6 Months Ended |
|---|---|---|
May 31, 2018 |
Jun. 30, 2018
USD ($)
MMBTU
|
|
| Transportation Service Agreement | ||
| Supply Commitment [Line Items] | ||
| Energy commitment (in MMBtus) | MMBTU | 491 | |
| Minimum remaining commitments under agreement | $ 38.7 | |
| Supply Agreement | ||
| Supply Commitment [Line Items] | ||
| Supply commitment term | 3 years | |
| Minimum remaining commitments under agreement | $ 25.2 | |
| Minimum | Transportation Service Agreement | ||
| Supply Commitment [Line Items] | ||
| Supply commitment term | 1 year | |
| Maximum | Transportation Service Agreement | ||
| Supply Commitment [Line Items] | ||
| Supply commitment term | 4 years |