Acquisitions and Dispositions (Details) - USD ($) $ in Thousands								3 Months Ended	8 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 16, 2016	Dec. 08, 2016	Dec. 01, 2016	Aug. 31, 2016	Apr. 25, 2016	Apr. 15, 2016	Mar. 31, 2018	Dec. 31, 2016	Dec. 31, 2017	Dec. 22, 2017	Nov. 06, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment							$ 46,900
South Bearhead Creek and Burr Ferry Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Participation Interest Sold in Oil and Gas Properties			25.00%				75.00%
Proceeds from Sale of Oil and Gas Property and Equipment			$ 7,100				$ 46,900
Buyer's Assumption of ARO			$ 2,400				$ 6,500
Masters Creek Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment						$ 100
Buyer's Assumption of ARO						$ 8,100
Sun TSH Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment					$ 900
Buyer's Assumption of ARO					$ 1,800
Lake Washington Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment				$ 37,000
Buyer's Assumption of ARO				$ 30,500
Royalty Package Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment		$ 500
AWP Olmos Wheeler Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment	$ 700
Buyer's Assumption of ARO	$ 600
AWP working interest acquisition [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Buyer's Assumption of ARO												$ 200
Bay De Chene [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Buyer's Assumption of ARO											$ 20,900
Purchase and sale contract											16,300
Cash to be released for purchase and sale contract										$ 10,000
Other Current Liabilities [Member] | Bay De Chene [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase and sale contract											11,300
Other Noncurrent Liabilities [Member] | Bay De Chene [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase and sale contract											$ 5,000
Subsequent Event [Member] | Bay De Chene [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash released for purchase and sale contract								$ 6,000
Successor [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to Acquire Oil and Gas Property									$ 0	$ 9,426