Supplemental Disclosures (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Supplemental Disclosures [Line Items]
Total accrued liabilities	$ 178,830	$ 174,348
Accrued evaluated and unproved and unevaluated property costs
Supplemental Disclosures [Line Items]
Total accrued liabilities	108,420	105,347
Accrued midstream property costs
Supplemental Disclosures [Line Items]
Total accrued liabilities	16,996	14,823
Accrued lease operating expenses
Supplemental Disclosures [Line Items]
Total accrued liabilities	18,651	12,611
Accrued interest on debt
Supplemental Disclosures [Line Items]
Total accrued liabilities	5,407	8,345
Accrued asset retirement obligations
Supplemental Disclosures [Line Items]
Total accrued liabilities	928	1,176
Accrued partners’ share of joint interest charges
Supplemental Disclosures [Line Items]
Total accrued liabilities	22,114	27,628
Other
Supplemental Disclosures [Line Items]
Total accrued liabilities	$ 6,314	$ 4,418