Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2016

Derivative Instruments Not Designated as Hedging Instruments [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

The following tables summarize the approximate volumes and average contract prices of contracts the Company had in place as of March 31, 2016:

Oil Swaps

Contract Period	NYMEX WTI Volumes	Weighted-Average  Contract Price
	(Bbls)	(per Bbl)
Second quarter 2016	1,752,000	$	86.73
Third quarter 2016	1,840,000	$	71.80
Fourth quarter 2016	1,399,000	$	67.73
2017	2,035,000	$	44.84
All oil swaps	7,026,000

Natural Gas Swaps

Contract Period	Sold Volumes	Weighted-Average  Contract Price		Purchased Volumes		Weighted- Average Contract Price		Net Volumes
	(MMBtu)	(per MMBtu)		(MMBtu)		(per MMBtu)		(MMBtu)
Second quarter 2016	20,780,000	$	3.40	—		$	—	20,780,000
Third quarter 2016	18,830,000	$	3.38	—		$	—	18,830,000
Fourth quarter 2016	18,988,000	$	3.69	—		$	—	18,988,000
2017	85,019,000	$	4.09	—		$	—	85,019,000
2018	30,606,000	$	4.27	(30,606,000	)	$	4.27	—
2019	24,415,000	$	4.34	(24,415,000	)	$	4.34	—
All gas swaps*	198,638,000			(55,021,000	)			143,617,000

*Total net volumes of natural gas swaps are comprised of IF El Paso Permian (2%), IF HSC (97%), and IF NNG Ventura (1%).

NGL Swaps

	OPIS Purity Ethane Mont Belvieu			OPIS Propane Mont Belvieu Non-TET			OPIS Normal Butane Mont Belvieu Non-TET			OPS Isobutane Mont Belvieu Non-TET
Contract Period	Volumes	Weighted-Average  Contract Price		Volumes	Weighted-Average Contract Price		Volumes	Weighted-Average Contract Price		Volumes	Weighted-Average Contract Price
	(Bbls)	(per Bbl)		(Bbls)	(per Bbl)		(Bbls)	(per Bbl)		(Bbls)	(per Bbl)
Second quarter 2016	828,000	$	8.28	949,000	$	19.64	208,000	$	24.02	174,000	$	24.68
Third quarter 2016	751,000	$	8.70	863,000	$	19.03	186,000	$	21.86	155,000	$	22.42
Fourth quarter 2016	687,000	$	8.71	792,000	$	18.53	170,000	$	21.86	141,000	$	22.42
2017	3,062,000	$	8.92	—	$	—	—	$	—	—	$	—
2018	2,435,000	$	10.18	—	$	—	—	$	—	—	$	—
2019	1,200,000	$	10.92	—	$	—	—	$	—	—	$	—
2020	539,000	$	11.13	—	$	—	—	$	—	—	$	—
Total NGL swaps	9,502,000			2,604,000			564,000			470,000

Schedule of fair value of derivatives in accompanying balance sheets

The following tables detail the fair value of derivatives recorded in the accompanying balance sheets, by category:

	As of March 31, 2016
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity contracts	Current assets	$	281,596	Current liabilities	$	8,211
Commodity contracts	Noncurrent assets	160,732		Noncurrent liabilities	78,514
Derivatives not designated as hedging instruments		$	442,328		$	86,725

	As of December 31, 2015
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity contracts	Current assets	$	367,710	Current liabilities	$	8
Commodity contracts	Noncurrent assets	120,701		Noncurrent liabilities	—
Derivatives not designated as hedging instruments		$	488,411		$	8

Schedule of the potential effects of master netting arrangements [Table Text Block]

The following table provides a reconciliation between the gross assets and liabilities reflected on the accompanying balance sheets and the potential effects of master netting arrangements on the fair value of the Company’s derivative contracts:

	Derivative Assets						Derivative Liabilities
	As of						As of
Offsetting of Derivative Assets and Liabilities	March 31, 2016			December 31, 2015			March 31, 2016			December 31, 2015
	(in thousands)
Gross amounts presented in the accompanying balance sheets	$	442,328		$	488,411		$	(86,725	)	$	(8	)
Amounts not offset in the accompanying balance sheets	(86,725		)	(8		)	86,725			8
Net amounts	$	355,603		$	488,403		$	—		$	—

Schedule of derivative (gain) loss

The following table summarizes the components of the derivative gain presented in the accompanying statements of operations:

	For the Three Months Ended March 31,
	2016			2015
	(in thousands)
Derivative settlement gain:
Oil contracts	$	(99,992	)	$	(106,214	)
Gas contracts	(41,053		)	(34,232		)
NGL contracts	(5,983		)	(20,783		)
Total derivative settlement gain	$	(147,028	)	$	(161,229	)
Total derivative (gain) loss:
Oil contracts	$	(10,432	)	$	(73,860	)
Gas contracts	(24,023		)	(82,339		)
NGL contracts	20,227			2,032
Total derivative gain	$	(14,228	)	$	(154,167	)