Long-Term Debt (Details) $ in Thousands							4 Months Ended	8 Months Ended	12 Months Ended
	Mar. 31, 2019	Jan. 26, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016	Jun. 30, 2016	Apr. 22, 2016 USD ($)	Apr. 22, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Oct. 03, 2012 USD ($)	Nov. 25, 2009 USD ($)	Jun. 01, 2007 USD ($)
Bankruptcy Proceedings
Plan of Reogranization, percentage of common stock lenders to receive net of backstop fee						88.50%	88.50%
Debtor-in-Possession Financing [Abstract]
Debtor-in-Possession Financing, Amount Arranged						$ 75,000	$ 75,000
Bank Borrowings
Liabilities subject to compromise, senior notes						906,000	$ 906,000
Line of Credit [Member]
Bank Borrowings
Percentage of applicable margin with federal fund rate							0.50%
Percentage of applicable margin with LIBOR							1.00%
Line of Credit [Member] | Minimum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt Instrument escalating basis spread on base rate							100
Line of Credit [Member] | Minimum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings
Debt instrument escalating rates for eurodollar rate loans							200
Line of Credit [Member] | Maximum [Member]
Bank Borrowings
Line of Credit Facility, Commitment Fee Percentage							0.50%
Line of Credit [Member] | Maximum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt Instrument escalating basis spread on base rate							200
Line of Credit [Member] | Maximum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings
Debt instrument escalating rates for eurodollar rate loans							300
New Credit Facility [Member] | Line of Credit [Member]
Bank Borrowings
Line of Credit Facility, Maximum Borrowing Capacity						500,000	$ 500,000
Line of Credit, current borrowing base						$ 320,000	320,000
Line of Credit, Required Security Interest on Oil and Gas Properties						95.00%
Line of Credit Facility, Non-Conforming Borrowing Base						$ 70,000
Line of Credit Facility, Conforming Borrowing Base						250,000
Debt, Weighted Average Interest Rate			7.90%					7.90%
Line of Credit, Covenant, Debt to EBITDA Ratio, Minimum				6.0
Line of Credit, Covenant, Current Ratio, Minimum					1.0
Line of Credit, Covenant, Liquidity Requirement, Minimum						10,000
New Credit Facility [Member] | Line of Credit [Member] | Minimum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Basis Spread on Base Rate During Non-Conforming Period			500
Debt Instrument Escalating Basis Spread on Base Rate After Non-Conforming Period			200
New Credit Facility [Member] | Line of Credit [Member] | Minimum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Rates for Eurodollar Rate Loans During Non-Conforming Period			600
Debt Instrument Escalating Rates for Eurodollar Rate Loans After Non-Conforming Period			300
New Credit Facility [Member] | Line of Credit [Member] | Maximum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Basis Spread on Base Rate During Non-Conforming Period			600
Debt Instrument Escalating Basis Spread on Base Rate After Non-Conforming Period			300
New Credit Facility [Member] | Line of Credit [Member] | Maximum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Rates for Eurodollar Rate Loans During Non-Conforming Period			700
Debt Instrument Escalating Rates for Eurodollar Rate Loans After Non-Conforming Period			400
Senior Notes Due 2017 [Member] | Senior Notes [Member]
Senior Notes
Stated rate of senior notes													7.125%
Percentage at which senior notes are issued, of par value													100.00%
Bank Borrowings
Long-Term Debt, excluding current maturities													$ 250,000
Liabilities subject to compromise, senior notes									$ 250,000
Senior Notes Due 2020 [Member] | Senior Notes [Member]
Senior Notes
Senior notes, issued												$ 225,000
Stated rate of senior notes												8.875%
Percentage at which senior notes are issued, of par value												98.389%
Effective interest rate on senior notes including discount												9.125%
Bank Borrowings
Liabilities subject to compromise, senior notes									225,000
Senior Notes Due 2022 [Member] | Senior Notes [Member]
Senior Notes
Senior notes, issued											$ 400,000
Stated rate of senior notes											7.875%
Bank Borrowings
Liabilities subject to compromise, senior notes									400,000
DIP Facility [Member]
Debtor-in-Possession Financing [Abstract]
Debtor-in-Possession Financing, Amount Arranged						$ 75,000	$ 75,000
Debtor-in-Possession Financing, Fee on Unused Borrowings						3.00%	3.00%
Subsequent Event [Member] | New Credit Facility [Member] | Line of Credit [Member]
Bank Borrowings
Line of Credit Facility, Conforming Borrowing Base		$ 250,000
Line of Credit, Covenant, Debt to EBITDA Ratio, Minimum	3.5
Subsequent Event [Member] | New Credit Facility [Member] | Line of Credit [Member] | Minimum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Basis Spread on Base Rate After Non-Conforming Period		200
Subsequent Event [Member] | New Credit Facility [Member] | Line of Credit [Member] | Minimum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Rates for Eurodollar Rate Loans After Non-Conforming Period		300
Subsequent Event [Member] | New Credit Facility [Member] | Line of Credit [Member] | Maximum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Basis Spread on Base Rate After Non-Conforming Period		300
Subsequent Event [Member] | New Credit Facility [Member] | Line of Credit [Member] | Maximum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings
Debt Instrument Escalating Rates for Eurodollar Rate Loans After Non-Conforming Period		400
Predecessor [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities									0
Total Debt									324,900
Capitalized interest on our unproved properties							$ 0		4,900	$ 5,000
Interest expense including commitment fees and amortization of debt issuance costs relating to the credit facility							13,347		75,870	73,207
Predecessor [Member] | Senior Notes [Member]
Bank Borrowings
Interest expense including commitment fees and amortization of debt issuance costs relating to the credit facility							0		70,800	70,700
Contractual Interest Expense on Prepetition Liabilities Not Recognized in Statement of Operations							21,600
Predecessor [Member] | Line of Credit [Member]
Bank Borrowings
Long-term Debt, Current Maturities									324,900
Commitment fees included in interest expense, net							0		500	800
Interest expense including commitment fees and amortization of debt issuance costs relating to the credit facility							6,800		9,400	$ 7,500
Predecessor [Member] | Senior Notes Due 2017 [Member] | Senior Notes [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities									0
Predecessor [Member] | Senior Notes Due 2020 [Member] | Senior Notes [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities									0
Predecessor [Member] | Senior Notes Due 2022 [Member] | Senior Notes [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities									0
Predecessor [Member] | DIP Facility [Member]
Debtor-in-Possession Financing [Abstract]
Debtor-in-Possession Financing, Commitment Fees Paid							900
Bank Borrowings
Interest expense including commitment fees and amortization of debt issuance costs relating to the credit facility							$ 6,400
Predecessor [Member] | Bank Borrowings [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities									$ 324,900
Successor [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities			$ 198,000					$ 198,000
Total Debt			198,000					198,000
Long-term Debt, Current Maturities			0					0
Capitalized interest on our unproved properties								500
Interest expense including commitment fees and amortization of debt issuance costs relating to the credit facility								15,310
Successor [Member] | New Credit Facility [Member] | Line of Credit [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities			198,000					198,000
Commitment fees included in interest expense, net								200
Successor [Member] | Senior Notes Due 2017 [Member] | Senior Notes [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities			0					0
Successor [Member] | Senior Notes Due 2020 [Member] | Senior Notes [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities			0					0
Successor [Member] | Senior Notes Due 2022 [Member] | Senior Notes [Member]
Bank Borrowings
Long-Term Debt, excluding current maturities			0					0
Successor [Member] | Bank Borrowings [Member]
Bank Borrowings
Total Debt			$ 198,000					$ 198,000