Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value Disclosures [Abstract]

Fair value hierarchy for financial instruments measured at fair value on a recurring basis

The fair value hierarchy for our financial assets and liabilities is shown by the following table:

	As of June 30, 2012								As of December 31, 2011
	Derivative assets			Derivative liabilities			Net assets (liabilities)		Derivative assets			Derivative liabilities			Net assets (liabilities)
Significant other observable inputs (Level 2)	$	40,221		$	(3,390	)	$	36,831	$	33,956		$	(11,012	)	$	22,944
Significant unobservable inputs (Level 3)	39,623			—			39,623		6,296			(1,247		)	5,049
Netting adjustments (1)	(3,125		)	3,125			—		(10,627		)	10,627			—
	$	76,719		$	(265	)	$	76,454	$	29,625		$	(1,632	)	$	27,993

___________

(1) Amounts represent the impact of master netting agreements that allow us to net settle positive and negative positions with the same counterparty.

Level 3 rollforward

Changes in the fair value of our collars classified as Level 3 in the fair value hierarchy during the six months ended June 30, 2012 and 2011 were: 

	For the six months ended June 30,
Net derivative assets	2012			2011
Beginning balance	$	5,049		$	1,509
Realized and unrealized gains (losses) included in non-hedge derivative gains (losses)	37,206			(181		)
Settlements received	(2,632		)	(490		)
Ending balance	$	39,623		$	838
Gains relating to instruments still held at the reporting date included in non-hedge derivative gains (losses) for the period	$	35,232		$	64

Fair value of other financial instruments

Our significant financial instruments, other than derivatives, consist primarily of cash and cash equivalents, accounts receivable, accounts payable, and long-term debt. We believe the carrying values of cash and cash equivalents, accounts receivable, and accounts payable approximate fair values due to the short-term maturities of these instruments.

The carrying value and estimated fair value of our long-term debt at June 30, 2012 and December 31, 2011 were as follows:

	June 30, 2012				December 31, 2011
Level 2	Carrying value		Estimated fair value		Carrying value		Estimated fair value
8.875% Senior Notes due 2017	$	—	$	—	$	323,342	$	326,625
9.875% Senior Notes due 2020	293,789		333,390		293,559		322,500
8.25% Senior Notes due 2021	400,000		424,000		400,000		402,400
7.625% Senior Notes due 2022	400,000		407,000		—		—
Senior secured revolving credit facility	35,000		35,000		—		—
Other secured long-term debt	18,748		18,748		17,672		17,672
	$	1,147,537	$	1,218,138	$	1,034,573	$	1,069,197

Concentrations of counterparty credit risk

we had significant commodity derivative net asset balances with the following counterparties:

	Percentage of
	future hedged
Counterparty	production
JP Morgan Chase Bank, N.A.	30	%
Societe Generale	20	%
Royal Bank of Canada	9	%
Macquarie Bank Limited	9	%
Crédit Agricole CIB	7	%
The Bank of Nova Scotia	6	%
	81	%