Supplemental Disclosures (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Supplemental Disclosures [Line Items]
Total accrued liabilities	$ 133,365	$ 174,348
Accrued evaluated and unproved and unevaluated property costs
Supplemental Disclosures [Line Items]
Total accrued liabilities	79,540	105,347
Accrued midstream property costs
Supplemental Disclosures [Line Items]
Total accrued liabilities	11,459	14,823
Accrued lease operating expenses
Supplemental Disclosures [Line Items]
Total accrued liabilities	14,209	12,611
Accrued interest on debt
Supplemental Disclosures [Line Items]
Total accrued liabilities	8,345	8,345
Accrued asset retirement obligations
Supplemental Disclosures [Line Items]
Total accrued liabilities	1,235	1,176
Accrued partners’ share of joint interest charges
Supplemental Disclosures [Line Items]
Total accrued liabilities	14,824	27,628
Other
Supplemental Disclosures [Line Items]
Total accrued liabilities	3,680	4,418
Accrued Cost to Issue Equity [Member]
Supplemental Disclosures [Line Items]
Total accrued liabilities	$ 73	$ 0