Accounts Receivable and Revenues from Contracts with Customers - Additional Information (Details) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended |
Jun. 30, 2018USD ($) | Jun. 30, 2017USD ($) | Jun. 30, 2018USD ($)Customer | Jun. 30, 2017USD ($)Customer | Dec. 31, 2017USD ($) |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Net Income (Loss) Available to Common Stockholders, Basic | $ (2,521) | $ 21,329 | $ 7,774 | $ 49,410 | |
Document Period End Date | | | Jun. 30, 2018 | | |
Sales Revenue | Customer Concentration Risk [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Number of major customers | Customer | | | 3 | 1 | |
Revenues, major customers | | | $ 157,800 | $ 64,600 | |
Concentration risk, percentage | | | 84.00% | 91.00% | |
Sales Revenue | Customer Concentration Risk [Member] | Major Customer 1 | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenues, major customers | | | $ 81,000 | | |
Concentration risk, percentage | | | 43.00% | | |
Sales Revenue | Customer Concentration Risk [Member] | Major Customer 2 | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenues, major customers | | | $ 41,000 | | |
Concentration risk, percentage | | | 22.00% | | |
Sales Revenue | Customer Concentration Risk [Member] | Major Customer 3 | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenues, major customers | | | $ 35,800 | | |
Concentration risk, percentage | | | 19.00% | | |
Accounts Receivable | Credit Concentration Risk | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Concentration risk, percentage | | | 75.00% | | 82.00% |
Accounts receivable, major customers | 41,900 | | $ 41,900 | | $ 32,100 |
Oil and Gas, Exploration and Production [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 101,716 | 32,351 | 172,974 | $ 62,424 | |
Oil and Condensate [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 5,533 | 2,043 | 8,479 | 4,345 | |
Natural Gas, Production [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 3,912 | 1,880 | 6,702 | 4,223 | |
Oil and Gas, Refining and Marketing [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 153 | | 245 | | |
Natural Gas, Gathering, Transportation, Marketing and Processing [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Cost of Goods and Services Sold | 4,574 | $ 2,555 | 7,933 | $ 5,106 | |
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Net Income (Loss) Available to Common Stockholders, Basic | (2,521) | | 7,774 | | |
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Oil and Gas, Exploration and Production [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 101,716 | | 172,974 | | |
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Oil and Condensate [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 6,103 | | 9,495 | | |
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Natural Gas, Production [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 3,912 | | 6,702 | | |
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Oil and Gas, Refining and Marketing [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax | 153 | | 245 | | |
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Natural Gas, Gathering, Transportation, Marketing and Processing [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Cost of Goods and Services Sold | 5,144 | | 8,949 | | |
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Net Income (Loss) Available to Common Stockholders, Basic, Increase (Decrease) | 0 | | 0 | | |
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Oil and Gas, Exploration and Production [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax, Increase (Decrease) | 0 | | 0 | | |
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Oil and Condensate [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax, Increase (Decrease) | (570) | | (1,016) | | |
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Natural Gas, Production [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax, Increase (Decrease) | 0 | | 0 | | |
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Oil and Gas, Refining and Marketing [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Revenue from Contract with Customer, Including Assessed Tax, Increase (Decrease) | 0 | | 0 | | |
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Natural Gas, Gathering, Transportation, Marketing and Processing [Member] | | | | | |
Accounts, Notes, Loans and Financing Receivable [Line Items] | | | | | |
Cost of Goods and Services Sold, Increase (Decrease) | $ (570) | | $ (1,016) | | |