Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2012

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	07/01/2012 - 12/31/2012		20,000		90.00		104.20	$	784
Oil	07/01/2012 - 12/31/2012		10,000		90.00		108.00		407
Oil	07/01/2012 - 12/31/2012		10,000		90.00		109.50		411
Oil	07/01/2012 - 12/31/2012		20,000		90.00		111.00		829
Oil	07/01/2012 - 12/31/2012		20,000		90.00		111.90		832
Oil	07/01/2012 - 12/31/2012		20,000		95.00		116.00		1,274
Oil	07/01/2012 - 03/31/2013		20,000		90.00		110.00		1,294
Oil	01/01/2013 - 12/31/2013		20,000		85.00		102.25		938
Oil	01/01/2013 - 12/31/2013		20,000		90.00		115.00		2,065
Oil	01/01/2013 - 12/31/2013		20,000		85.00		110.40		1,356
Oil	01/01/2013 - 12/31/2013		20,000		85.00		108.80		1,292
Oil	01/01/2013 - 06/30/2014		8,000		90.00		114.00		1,258
Oil	01/01/2013 - 06/30/2014		12,000		90.00		115.50		1,930
Total Oil								$	14,670
Commodity	Calculation Period	Notional Quantity (MMBtu/month)		Price Floor ($/MMBtu)		Price Ceiling ($/MMBtu)		Fair Value of Asset (Liability) (thousands)
Natural Gas	07/01/2012 - 12/31/2012		300,000		4.50		5.60	$	2,801
Natural Gas	07/01/2012 - 12/31/2012		150,000		4.25		6.17		1,187
Natural Gas	07/01/2012 - 12/31/2012		70,000		2.50		3.34		(26	)
Natural Gas	07/01/2012 - 07/31/2013		150,000		4.50		5.75		2,557
Natural Gas	07/01/2012 - 12/31/2013		100,000		3.00		3.83		(63	)
Total Natural Gas									6,456
Total open costless collar contracts								$	21,126

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	June 30, 2012		December 31, 2011
Derivative Instrument
Oil	Current assets: Derivative instruments	$	9,595	$	—
Oil	Other assets: Derivative instruments		5,075		—
Oil	Current liabilities: Derivative instruments		—		(171	)
Oil	Long-term liabilities: Derivative instruments		—		(383	)
Natural Gas	Current assets: Derivative instruments		6,438		8,989
Natural Gas	Other assets: Derivative instruments		18		847
Total		$	21,126	$	9,282

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

		Three Months Ended June  30,					Six Months Ended June 30,
Type of Instrument	Location in Statement of Operations	2012			2011		2012			2011
Derivative Instrument
Oil	Revenue: Realized gain on derivatives	$	719		$	—	$	719		$	—
Natural Gas	Revenues: Realized gain on derivatives		3,994			952		7,057			2,802
Realized gain on derivatives			4,713			952		7,776			2,802
Oil	Revenues: Unrealized gain on derivatives		20,483			—		15,223			—
Natural Gas	Revenues: Unrealized (loss) gain on derivatives		(5,369	)		332		(3,379	)		(1,336	)
Unrealized gain (loss) on derivatives			15,114			332		11,844			(1,336	)
Total		$	19,827		$	1,284	$	19,620		$	1,466