Revenues - Performance Obligation Payment Terms (Details)
6 Months Ended
Jun. 30, 2018
Natural Gas and NGL sales | Minimum  
Disaggregation of Revenue [Line Items]  
Performance obligations billing cycle 30 days
Natural Gas and NGL sales | Maximum  
Disaggregation of Revenue [Line Items]  
Performance obligations billing cycle 90 days
Oil sales  
Disaggregation of Revenue [Line Items]  
Performance obligations billing cycle 30 days