Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 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 June 30, 2016:

Oil Swaps

Contract Period	NYMEX WTI Volumes	Weighted-Average  Contract Price
	(MBbls)	(per Bbl)
Third quarter 2016	1,840	$	71.80
Fourth quarter 2016	1,399	$	67.73
2017	3,053	$	45.61
All oil swaps	6,292

Oil Collars

Contract Period	NYMEX WTI  Volumes	Weighted- Average Floor  Price		Weighted- Average Ceiling  Price
	(MBbls)	(per Bbl)		(per Bbl)
Third quarter 2016	672	$	40.00	$	51.57
Fourth quarter 2016	881	$	40.00	$	51.52
2017	1,018	$	45.00	$	51.02
All oil collars	2,571

Natural Gas Swaps

Contract Period	Sold Volumes	Weighted-Average  Contract Price		Purchased Volumes		Weighted- Average Contract Price		Net Volumes
	(BBtu)	(per MMBtu)		(BBtu)		(per MMBtu)		(BBtu)
Third quarter 2016	25,724	$	3.13	—		$	—	25,724
Fourth quarter 2016	26,700	$	3.34	—		$	—	26,700
2017	88,894	$	4.04	—		$	—	88,894
2018	53,048	$	3.75	(30,606	)	$	4.27	22,442
2019	24,415	$	4.34	(24,415	)	$	4.34	—
All gas swaps*	218,781			(55,021	)			163,760

*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
	(MBbls)	(per Bbl)		(MBbls)	(per Bbl)		(MBbls)	(per Bbl)		(MBbls)	(per Bbl)
Third quarter 2016	751	$	8.70	863	$	19.03	248	$	22.90	200	$	23.24
Fourth quarter 2016	687	$	8.71	792	$	18.53	226	$	22.91	182	$	23.25
2017	3,062	$	8.92	721	$	20.01	—	$	—	—	$	—
2018	2,435	$	10.18	—	$	—	—	$	—	—	$	—
2019	1,200	$	10.92	—	$	—	—	$	—	—	$	—
2020	539	$	11.13	—	$	—	—	$	—	—	$	—
Total NGL swaps	8,674			2,376			474			382

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 June 30, 2016
	Derivative Assets			Derivative Liabilities
	Balance Sheet  Classification	Fair Value		Balance Sheet  Classification	Fair Value
	(in thousands)
Commodity contracts	Current assets	$	145,576	Current liabilities	$	63,492
Commodity contracts	Noncurrent assets	113,119		Noncurrent liabilities	104,660
Derivatives not designated as hedging instruments		$	258,695		$	168,152

	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	June 30, 2016			December 31, 2015			June 30, 2016			December 31, 2015
	(in thousands)
Gross amounts presented in the accompanying balance sheets	$	258,695		$	488,411		$	(168,152	)	$	(8	)
Amounts not offset in the accompanying balance sheets	(158,955		)	(8		)	158,955			8
Net amounts	$	99,740		$	488,403		$	(9,197	)	$	—

Schedule of derivative (gain) loss

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

	For the Three Months Ended June 30,						For the Six Months Ended June 30,
	2016			2015			2016			2015
	(in thousands)
Derivative settlement (gain) loss:
Oil contracts	$	(72,164	)	$	(73,915	)	$	(172,156	)	$	(180,129	)
Gas contracts (1)	(31,439		)	(38,880		)	(72,492		)	(73,112		)
NGL contracts	1,893			—			(4,090		)	(20,783		)
Total derivative settlement (gain) loss	$	(101,710	)	$	(112,795	)	$	(248,738	)	$	(274,024	)
Total derivative (gain) loss:
Oil contracts	$	60,773		$	66,749		$	50,341		$	(7,111	)
Gas contracts	62,489			6,070			38,466			(76,269		)
NGL contracts	40,089			8,110			60,316			10,142
Total derivative (gain) loss:	$	163,351		$	80,929		$	149,123		$	(73,238	)