Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Fair Value Summary of Long-Term Debt with Fixed Interest Rates

The following table summarizes the fair value of our long-term debt with fixed interest rates, which is estimated based on the published market prices for these debt obligations, as of the dates presented:

	As of
	September 30, 2014				December 31, 2013
	Fair Value		Carrying Value		Fair Value		Carrying Value
Senior Notes due 2019	$	300,750	$	300,000	$	307,500	$	300,000
Senior Notes due 2020	821,500		775,000		837,969		775,000
	$	1,122,250	$	1,075,000	$	1,145,469	$	1,075,000

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following tables summarize the valuation of those assets and liabilities as of the dates presented:

	As of September 30, 2014
	Fair Value			Fair Value Measurement Classification
Description	Measurement			Level 1			Level 2			Level 3
Assets:
Commodity derivative assets – current	$	13,680		$	—		$	13,680		$	—
Commodity derivative assets – noncurrent	8,572			—			8,572			—
Assets of SERP	4,021			4,021			—			—
Liabilities:
Commodity derivative liabilities – current	(1,045		)	—			(1,045		)	—
Commodity derivative liabilities – noncurrent	—			—			—			—
Deferred compensation – SERP obligations	(4,125		)	(4,125		)	—			—

	As of December 31, 2013
	Fair Value			Fair Value Measurement Classification
Description	Measurement			Level 1			Level 2			Level 3
Assets:
Commodity derivative assets – current	$	3,830		$	—		$	3,830		$	—
Commodity derivative assets – noncurrent	1,552			—			1,552			—
Assets of SERP	3,734			3,734			—			—
Liabilities:
Commodity derivative liabilities – noncurrent	(10,141		)	—			(10,141		)	—
Deferred compensation – SERP obligations	(3,879		)	(3,879		)	—			—