Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value Measurements [Abstract]

Fair Value Hierarchy Table for Assets and Liabilities measured at Fair Value

	Fair Value Measurements at June 30, 2012 using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Total Carrying Value as of June 30, 2012
Trading securities held in the deferred compensation plans	$	56,345	$	—		$	—	$	56,345
Derivatives – swaps		—		134,629			—		134,629
– collars		—		212,320			—		212,320
– call options		—		(4,722	)		—		(4,722	)
– put options		—		1,071			—		1,071

	Fair Value Measurements at December 31, 2011 using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Total Carrying Value as of December 31, 2011
Trading securities held in the deferred compensation plans	$	50,237	$	—		$	—	$	50,237
Derivatives – swaps		—		69,054			—		69,054
– collars		—		211,621			—		211,621
– call options		—		(29,348	)		—		(29,348	)

Carrying amounts and Fair values of Financial Instruments

	June 30, 2012						December 31, 2011
	Carrying Value			Fair Value			Carrying Value			Fair Value
Assets:
Commodity swaps, collars, call and put options	$	348,986		$	348,986		$	251,500		$	251,500
Marketable securities (a)		56,345			56,345			50,237			50,237
Liabilities:
Commodity swaps, collars, call and put options		(5,688	)		(5,688	)		(173	)		(173	)
Bank credit facility (b)		(235,000	)		(235,000	)		(187,000	)		(187,000	)
7.50% senior subordinated notes due 2017 (b)		(250,000	)		(261,250	)		(250,000	)		(265,625	)
7.25% senior subordinated notes due 2018 (b)		(250,000	)		(265,000	)		(250,000	)		(267,500	)
8.00% senior subordinated notes due 2019 (b)		(288,562	)		(327,750	)		(287,967	)		(334,500	)
6.75% senior subordinated notes due 2020 (b)		(500,000	)		(542,500	)		(500,000	)		(555,000	)
5.75% senior subordinated notes due 2021 (b)		(500,000	)		(522,500	)		(500,000	)		(541,250	)
5.00% senior subordinated notes due 2022 (b)		(600,000	)		(592,500	)		—			—

^(a) Marketable securities, which are held in our deferred compensation plans, and are actively traded on major exchanges.

^(b) The book value of our bank debt approximates fair value because of its floating rate structure. The fair value of our senior subordinated notes is based on end of period market quotes which are Level 2 market values.