Financial Instruments - Schedule of Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands		Jun. 30, 2020	Dec. 31, 2019
Oil and Natural Gas Derivatives
Debt Instrument [Line Items]
Carrying Amount		$ 40,442	$ (11,594)
Fair Value		40,442	(11,594)
11.00% Second-Priority Senior Secured Notes – due April 2022
Debt Instrument [Line Items]
Carrying Amount	[1]	346,642	383,871
Fair Value	[1]	329,680	401,128
7.50% Senior Notes – due May 2022
Debt Instrument [Line Items]
Carrying Amount		6,060	6,060
Fair Value		4,236	5,030
Bank Credit Facility – matures May 2022
Debt Instrument [Line Items]
Carrying Amount		644,339	343,050
Fair Value		$ 650,000	$ 350,000

[1] ^{The carrying amounts are net of discount and deferred financing costs.}