Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

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
	March 31, 2015				December 31, 2014
	Fair Value		Carrying Value		Fair Value		Carrying Value
Senior Notes due 2019	$	271,500	$	300,000	$	234,000	$	300,000
Senior Notes due 2020	720,750		775,000		620,000		775,000
	$	992,250	$	1,075,000	$	854,000	$	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 March 31, 2015
	Fair Value			Fair Value Measurement Classification
Description	Measurement			Level 1			Level 2		Level 3
Assets:
Commodity derivative assets – current	$	118,409		$	—		$	118,409	$	—
Commodity derivative assets – noncurrent	31,844			—			31,844		—
Assets of SERP	4,216			4,216			—		—
Liabilities:
Deferred compensation – SERP obligations	(4,269		)	(4,269		)	—		—

	As of December 31, 2014
	Fair Value			Fair Value Measurement Classification
Description	Measurement			Level 1			Level 2		Level 3
Assets:
Commodity derivative assets – current	$	128,981		$	—		$	128,981	$	—
Commodity derivative assets – noncurrent	35,897			—			35,897		—
Assets of SERP	4,123			4,123			—		—
Liabilities:
Deferred compensation – SERP obligations	(4,178		)	(4,178		)	—		—