Long-Term Debt (Details)			3 Months Ended
	Dec. 15, 2017 USD ($)	Apr. 19, 2017 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Apr. 20, 2018 USD ($)	Dec. 31, 2017 USD ($)
Bank Borrowings
Payments of Debt Issuance Costs			$ 317,000	$ 0
Long-term Debt, excluding current maturities			245,371,000			$ 265,325,000
Gross interest expense including amortization of debt issuance costs			5,890,000	3,607,000
Second Lien [Abstract]
Long-term debt, gross			253,000,000			273,000,000
New Credit Facility [Member]
Bank Borrowings
Debt Issuance Costs, Net			5,200,000			5,500,000
Second Lien Notes [Member]
Bank Borrowings
Debt Issuance Costs, Net			5,688,000			5,683,000
Long-term Debt, excluding current maturities	$ 198,000,000		200,000,000			200,000,000
Debt instrument escalating basis spread on base rate	50
Gross interest expense including amortization of debt issuance costs			4,700,000
Second Lien [Abstract]
Long-term debt, gross	$ 200,000,000
Debt Instrument, Unamortized Discount	(2,000,000)		(1,941,000)			(1,992,000)
Additional notes issuable	$ 100,000,000
Additional interest in the event of default	0.020
Make whole premium during years 1 and 2	0.02
Make whole premium during year 3	0.02
Make whole premium during year 4	0.01
Second Lien, Required Security Interest on Proved Reserves	85.00%
Second Lien, Required Security Interest on Oil and Gas Properties	85.00%
Second Lien, Asset Coverage Ratio, Minimum	1.3
Second Lien, Covenant, Debt to EBITDA Ratio, Minimum	4.5
Long-term debt, net						192,400,000
Second Lien Notes [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt instrument escalating basis spread on base rate	0.065
Second Lien Notes [Member] | London Interbank Offered Rate (LIBOR) [Member]
Bank Borrowings
Debt instrument escalating basis spread on base rate	0.075
Line of Credit [Member]
Bank Borrowings
Capitalized interest on our unproved properties			400,000	200,000
Line of Credit [Member] | New Credit Facility [Member]
Bank Borrowings
Long-term Debt, excluding current maturities			53,000,000			$ 73,000,000
Line of Credit Facility, Maximum Borrowing Capacity		$ 600,000,000
Line of Credit, Letters of Credit Issuable		$ 25,000,000
Commitment fee basis points for the credit facility		0.50%
Line of Credit, Additional Interest Due to Payment Default		2.00%
Line of Credit, Required Security Interest on Oil and Gas Properties		85.00%
Line of Credit, Covenant, Debt to EBITDA Ratio, Minimum		4.0
Line of Credit, Covenant, Current Ratio, Minimum		1.0
Gross interest expense including amortization of debt issuance costs			5,900,000	3,600,000
Commitment fees included in interest expense, net			$ 300,000	$ 100,000
Line of Credit [Member] | New Credit Facility [Member] | Minimum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt instrument escalating basis spread on base rate		0.0125
Debt Instrument Escalating Rates for Eurodollar Rate Loans		0.0225
Line of Credit [Member] | New Credit Facility [Member] | Maximum [Member] | Alternative Base Interest Rate [Member]
Bank Borrowings
Debt instrument escalating basis spread on base rate		0.0225
Debt Instrument Escalating Rates for Eurodollar Rate Loans		0.0325
Subsequent Event [Member] | Line of Credit [Member] | New Credit Facility [Member]
Bank Borrowings
Line of Credit Facility, Current Borrowing Capacity					$ 330,000,000
Decrease in applicable margin to calculate interest					$ 50