Derivative Financial Instruments (Tables) (Open costless collar contracts [Member])

9 Months Ended

Sep. 30, 2012

Open costless collar contracts [Member]

Open Option Contracts Written [Line Items]

Summary of contracts for oil and natural gas

Commodity	Calculation Period	Notional Quantity (Bbl/month)		Price Floor ($/Bbl)		Price Ceiling ($/Bbl)		Fair Value  of Asset (thousands)
Oil	10/01/2012 - 12/31/2012		20,000		90.00		104.20	$	113
Oil	10/01/2012 - 12/31/2012		10,000		90.00		108.00		65
Oil	10/01/2012 - 12/31/2012		10,000		90.00		109.50		68
Oil	10/01/2012 - 12/31/2012		20,000		90.00		111.00		139
Oil	10/01/2012 - 12/31/2012		20,000		90.00		111.90		141
Oil	10/01/2012 - 12/31/2012		20,000		95.00		116.00		291
Oil	10/01/2012 - 03/31/2013		20,000		90.00		110.00		356
Oil	01/01/2013 - 12/31/2013		20,000		85.00		102.25		61
Oil	01/01/2013 - 12/31/2013		20,000		90.00		115.00		1,233
Oil	01/01/2013 - 12/31/2013		20,000		85.00		110.40		598
Oil	01/01/2013 - 12/31/2013		20,000		85.00		108.80		515
Oil	01/01/2013 - 06/30/2014		8,000		90.00		114.00		794
Oil	01/01/2013 - 06/30/2014		12,000		90.00		115.50		1,242
Total Oil (open costless collar contracts)								$	5,616
Commodity	Calculation Period	Notional Quantity (MMBtu/month)		Price Floor ($/MMBtu)		Price Ceiling ($/MMBtu)		Fair Value of Asset (Liability) (thousands)
Natural Gas	10/01/2012 - 12/31/2012		300,000		4.50		5.60	$	1,067
Natural Gas	10/01/2012 - 12/31/2012		150,000		4.25		6.17		424
Natural Gas	10/01/2012 - 12/31/2012		70,000		2.50		3.34		(36	)
Natural Gas	10/01/2012 - 07/31/2013		150,000		4.50		5.75		1,398
Natural Gas	10/01/2012 - 12/31/2013		100,000		3.00		3.83		(381	)
Total Natural Gas (open costless collar contracts)								$	2,472

Commodity	Calculation Period	Notional  Quantity (Gal/month)		Fixed Price ($/Gal)		Fair Value  of Asset (Liability) (thousands)
Purity Ethane	10/01/2012 - 12/31/2012		55,700		0.333	$	—
Purity Ethane	10/01/2012 - 12/31/2012		55,700		0.337		—
Propane	10/01/2012 - 12/31/2012		27,000		0.945		1
Propane	10/01/2012 - 12/31/2012		27,000		0.992		5
Normal Butane	10/01/2012 - 12/31/2012		7,500		1.465		—
Normal Butane	10/01/2012 - 12/31/2012		7,500		1.580		3
Isobutane	10/01/2012 - 12/31/2012		4,000		1.535		(2	)
Isobutane	10/01/2012 - 12/31/2012		4,000		1.675		(1	)
Natural Gasoline	10/01/2012 - 12/31/2012		6,000		2.095		2
Natural Gasoline	10/01/2012 - 12/31/2012		6,000		2.150		3
Purity Ethane	01/01/2013 - 12/31/2013		110,000		0.335		(41	)
Purity Ethane	01/01/2013 - 12/31/2013		110,000		0.355		(15	)
Propane	01/01/2013 - 12/31/2013		53,000		0.953		7
Propane	01/01/2013 - 12/31/2013		53,000		1.001		38
Normal Butane	01/01/2013 - 12/31/2013		14,700		1.455		(3	)
Normal Butane	01/01/2013 - 12/31/2013		14,700		1.560		16
Isobutane	01/01/2013 - 12/31/2013		7,000		1.515		(7	)
Isobutane	01/01/2013 - 12/31/2013		7,000		1.625		3
Natural Gasoline	01/01/2013 - 12/31/2013		12,000		2.085		17
Natural Gasoline	01/01/2013 - 12/31/2013		12,000		2.102		19
Total NGL’s (open swap contracts)						$	45
Total open derivative financial instruments						$	8,133

Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets

Type of Instrument	Location in Balance Sheet	September 30, 2012			December 31, 2011
Derivative Instrument
Oil	Current assets: Derivative instruments	$	3,736		$	—
Oil	Other assets: Derivative instruments		1,880			—
Oil	Current liabilities: Derivative instruments		—			(171	)
Oil	Long-term liabilities: Derivative instruments		—			(383	)
Natural Gas	Current assets: Derivative instruments		2,610			8,989
Natural Gas	Other assets: Derivative instruments		—			847
Natural Gas	Long-term liabilities: Derivative instruments		(138	)		—
NGL’s	Current assets: Derivative instruments		49			—
NGL’s	Long-term liabilities: Derivative instruments		(4	)		—
Total		$	8,133		$	9,282

Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations

		Three Months Ended September 30,					Nine Months Ended September 30,
Type of Instrument	Location in Statement of Operations	2012			2011		2012			2011
Derivative Instrument
Oil	Revenues: Realized gain on derivatives	$	374		$	—	$	1,093		$	—
Natural Gas	Revenues: Realized gain on derivatives		2,996			1,435		10,053			4,237
NGL’s	Revenues: Realized gain on derivatives		1			—		1			—
Realized gain on derivatives			3,371			1,435		11,147			4,237
Oil	Revenues: Unrealized (loss) gain on derivatives		(9,053	)		—		(7,364	)		—
Natural Gas	Revenues: Unrealized (loss) gain on derivatives		(3,985	)		2,870		6,170			1,534
NGL’s	Revenues: Unrealized gain (loss) on derivatives		45			—		45			—
Unrealized (loss) gain on derivatives			(12,993	)		2,870		(1,149	)		1,534
Total		$	(9,622	)	$	4,305	$	9,998		$	5,771