Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended										3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Y	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Eight Point Six Two Five Percent Senior Notes [Member]	Feb. 28, 2012 Eight Point Six Two Five Percent Senior Notes [Member]	Nov. 30, 2011 Eight Point Six Two Five Percent Senior Notes [Member]	Jun. 30, 2011 Eight Point Six Two Five Percent Senior Notes [Member]	Nov. 30, 2010 Eight Point Six Two Five Percent Senior Notes [Member]	Jun. 30, 2012 8.625% Senior Notes Due 2018 [Member]	Jun. 30, 2012 4.375% Convertible Senior Notes Due 2028 [Member]	Jun. 30, 2012 Stock Options [Member]	Jun. 30, 2012 Restricted Stock Awards And Units [Member]	Jun. 30, 2012 Stock Options And SARs [Member]	Jun. 30, 2012 Restricted Stock Granted To Contractors [Member]	Jun. 30, 2012 Minimum [Member] Stock Appreciation Rights (SARs) [Member]	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Maximum [Member] Stock Appreciation Rights (SARs) [Member]
Summary Of Significant Accounting Policies [Line Items]
Allowance for doubtful accounts receivable	$ 1,900,000		$ 1,900,000		$ 2,300,000
Internal costs capitalized	4,100,000	3,100,000	7,500,000	5,500,000
Average DD&A per Mcfe (in USD per Unit of Production)	3.02	1.84	2.66	1.70
Average DD&A Per Boe (in USD per Boe)	18.12	11.04	15.96	10.20
Capitalized interest costs associated with unevaluated leasehold and seismic costs	7,809,000	5,649,000	13,832,000	10,909,000
Reserves discount factor	10.00%
Property and equipment estimated useful life, minimum, in years			5
Property and equipment estimated useful life, maximum, in years			10
Vesting period, in years															three	three
Vesting period for restricted stock awards and units in stock-based compensation, minimum, in years														one
Vesting period for restricted stock awards and units in stock-based compensation, maximum, in years																		three
Expiration period after date of grant, in years													ten				four		seven
Debt instrument interest rate						8.625%					8.625%	4.375%
Senior Notes	$ 600,000,000		$ 600,000,000		$ 600,000,000		$ 200,000,000	$ 200,000,000	$ 400,000,000	$ 400,000,000