Debt (Details) $ in Thousands							3 Months Ended		5 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2019	Jan. 01, 2017	Jun. 30, 2016	Apr. 22, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 01, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2016	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015 USD ($)	Nov. 02, 2015 USD ($)	May. 01, 2015 USD ($)	Oct. 03, 2012 USD ($)	Nov. 30, 2011 USD ($)	Nov. 25, 2009 USD ($)	Jun. 01, 2007 USD ($)
Debt Instrument [Line Items]
Long-term Debt					$ 339,900		$ 339,900						$ 324,900
Long-term Debt, Excluding Current Maturities					0		0						0
Bank Borrowings and New Credit Facility
Liabilities Subject to Compromise, Debt and Accrued Interest					905,629		905,629						905,629
Long-term Debt, Current Maturities					339,900		339,900
Interest expense including amortization of debt issuance costs							8,066	$ 18,228
Capitalized interest on our unproved properties							0	1,200
DIP Facility [Member]
Bank Borrowings and New Credit Facility
Interest expense including amortization of debt issuance costs							1,900
Debtor-in-Possession Financing
Debtor-in-Possession Financing, Amount Currently Available					30,000		30,000
Debtor-in-Possession Financing, Borrowings Outstanding					15,000		15,000
Debtor-in-Possession Financing, Unused Borrowings					$ 45,000		$ 45,000
DIP Financing, percentage of applicable margin with LIBOR							12.00%
DIP Financing, percentage of applicable margin with ABR							11.00%
Debtor-in-Possession Financing, Fee on Unused Borrowings					3.00%		3.00%
Debtor-in-Possession Financing, Commitment Fees Paid							$ 900
Plan of Reorganization, backstop fee					7.50%		7.50%
DIP Financing, fee paid on drawdowns against DIP facility					5.00%		5.00%
DIP Financing, net proceeds after drawdown fee					95.00%		95.00%
Senior Notes [Member]
Bank Borrowings and New Credit Facility
Interest expense including amortization of debt issuance costs							$ 0	17,700
Senior Notes [Member] | Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities					$ 0		0						0
Bank Borrowings and New Credit Facility
Liabilities Subject to Compromise, Debt and Accrued Interest					250,000		250,000						250,000
Senior Notes
Senior notes, issued																			$ 250,000
Debt instrument, interest rate, stated percentage																			7.125%
Percentage at which senior notes are issued, of par value																			100.00%
Debt Instrument, Periodic Payment, Interest						$ 8,900
Senior Notes [Member] | Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities					0		0						0
Bank Borrowings and New Credit Facility
Liabilities Subject to Compromise, Debt and Accrued Interest					225,000		225,000						225,000
Senior Notes
Senior notes, issued																		$ 225,000
Debt instrument, interest rate, stated percentage																		8.875%
Original unamortized issuance discount on senior notes																		$ 3,600
Percentage at which senior notes are issued, of par value																		98.389%
Effective Interest Rate On Senior Notes Including Discount																		9.125%
Senior Notes [Member] | Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities					0		0						0
Bank Borrowings and New Credit Facility
Liabilities Subject to Compromise, Debt and Accrued Interest					400,000		400,000						400,000
Senior Notes
Senior notes, issued																$ 400,000	$ 250,000
Debt instrument, interest rate, stated percentage																7.875%
Original unamortized issuance discount on senior notes																	$ 2,100
Percentage at which senior notes are issued, of par value																	99.156%
Effective Interest Rate On Senior Notes Including Discount																	8.00%
Senior Notes [Member] | Additional Senior Notes Due 2022 [Member]
Senior Notes
Senior notes, issued																$ 150,000
Percentage at which senior notes are issued, of par value																105.00%
Effective Interest Rate On Senior Notes Including Discount																6.993%
Line of Credit [Member]
Bank Borrowings and New Credit Facility
Long-term Debt, Current Maturities					324,900		$ 324,900						$ 324,900
Debt Issuance Cost Write-Off					2,400
Line of Credit Facility, Current Borrowing Capacity														$ 330,000	$ 375,000
Line of Credit, current commitment amount														$ 330,000	$ 375,000
Percentage of applicable margin with federal fund rate							0.50%
Percentage of applicable margin with LIBOR							1.00%
Lead bank's prime rate							3.50%
Commitment fee basis points for the credit facility							0.50%
Interest expense including amortization of debt issuance costs							$ 6,100	1,700
Commitment fees included in interest expense, net								$ 200
Maximum level of cash dividends in any fiscal year					15,000		15,000
Equity Restrictions					$ 50,000		$ 50,000
Line of credit, required security interest on oil and gas properties					95.00%
Line of Credit [Member] | Minimum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings and New Credit Facility
Debt instrument escalating basis spread on base rate							100
Line of Credit [Member] | Minimum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings and New Credit Facility
Debt Instrument Escalating Rates for Eurodollar Rate Loans							200
Line of Credit [Member] | Maximum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings and New Credit Facility
Debt instrument escalating basis spread on base rate							200
Line of Credit [Member] | Maximum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings and New Credit Facility
Debt Instrument Escalating Rates for Eurodollar Rate Loans							300
Subsequent Event [Member]
Bank Borrowings and New Credit Facility
Liabilities Subject to Compromise, Debt and Accrued Interest				$ 905,629
Debtor-in-Possession Financing
Plan of Reogranization, percentage of common stock lenders to receive net of backstop fee				88.50%
Debtor-in-Possession Financing, Amount Arranged				$ 75,000
Plan of Reorganization, backstop fee				7.50%
Subsequent Event [Member] | Line of Credit [Member]
Bank Borrowings and New Credit Facility
Line of credit, covenant, working capital ratio, minimum		1.0										0.5
Debt instrument, covenant, interest coverage ratio, minimum		2.0								1.30	1.15
Line of Credit, Covenant, Senior Secured Leverage Ratio, Maximum		2.5								3.0	3.5
Subsequent Event [Member] | Line of Credit [Member] | New Credit Facility [Member]
Bank Borrowings and New Credit Facility
Line of Credit Facility, Current Borrowing Capacity				$ 320,000
Line of Credit Facility, Maximum Borrowing Capacity				500,000
Line of Credit Facility, Non-Conforming Borrowing Base				70,000
Line of Credit Facility, Conforming Borrowing Base				250,000
Line of Credit, Covenant, Debt to EBITDA Ratio, Minimum	3.5								6.5
Line of Credit, Covenant, Current Ratio, Minimum			1.0
Line of Credit, Covenant, Liquidity Requirement, Minimum				$ 10,000
Subsequent Event [Member] | Line of Credit [Member] | New Credit Facility [Member] | Minimum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings and New Credit Facility
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
Subsequent Event [Member] | Line of Credit [Member] | New Credit Facility [Member] | Minimum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings and New Credit Facility
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
Subsequent Event [Member] | Line of Credit [Member] | New Credit Facility [Member] | Maximum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings and New Credit Facility
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
Subsequent Event [Member] | Line of Credit [Member] | New Credit Facility [Member] | Maximum [Member] | Eurodollar Interest Rate [Member]
Bank Borrowings and New Credit Facility
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