Disclosures About Fair Value Measurements (Assets And Liabilities That Are Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2008	Dec. 31, 2011 5.875% Senior Notes Due 2016 [Member]	Dec. 31, 2011 6.65% Senior Notes Due 2017 [Member]	Dec. 31, 2011 6.875% Senior Notes Due 2018 [Member]	Dec. 31, 2011 7.50% Senior Notes Due 2020 [Member]	Dec. 31, 2011 7.20% Senior Notes Due 2028 [Member]	Dec. 31, 2011 2.875% Convertible Senior Notes Due 2038 [Member]	Dec. 31, 2011 Trading Securities [Member]	Dec. 31, 2010 Trading Securities [Member]	Dec. 31, 2011 Commodity Derivatives [Member]	Dec. 31, 2010 Commodity Derivatives [Member]	Dec. 31, 2011 Deferred Compensation Plan Assets [Member]	Dec. 31, 2010 Deferred Compensation Plan Assets [Member]	Dec. 31, 2011 Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	Dec. 31, 2010 Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	Dec. 31, 2011 Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] Trading Securities [Member]	Dec. 31, 2010 Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] Trading Securities [Member]	Dec. 31, 2011 Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] Deferred Compensation Plan Assets [Member]	Dec. 31, 2010 Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] Deferred Compensation Plan Assets [Member]	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member] Trading Securities [Member]	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member] Trading Securities [Member]	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member] Commodity Derivatives [Member]	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member] Commodity Derivatives [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member] Trading Securities [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member] Commodity Derivatives [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member] Deferred Compensation Plan Assets [Member]	Dec. 31, 2011 Liability Awards [Member]	Dec. 31, 2010 Liability Awards [Member]	Dec. 31, 2011 Liability Awards [Member] Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	Dec. 31, 2010 Liability Awards [Member] Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	Dec. 31, 2010 Liability Awards [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Interest Rate Derivatives [Member]	Dec. 31, 2010 Interest Rate Derivatives [Member]	Dec. 31, 2011 Interest Rate Derivatives [Member] Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Interest Rate Derivatives [Member] Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Interest Rate Derivatives [Member] Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, (Fair Value, Total)	$ 522,404	$ 359,319								$ 425	$ 467	$ 482,075	$ 304,434	$ 39,904	$ 36,162	$ 40,161	$ 36,478	$ 257	$ 316	$ 39,904	$ 36,162	$ 482,243	$ 322,841	$ 168	$ 151	$ 482,075	$ 304,434											$ 18,256		$ 18,256
Liabilities, (Fair Value, Total)	$ 117,183	$ 142,471										$ 92,322	$ 136,867			$ 9,207	$ 4,900					$ 107,976	$ 128,015			$ 92,322	$ 127,311	$ 9,556		$ 9,556		$ 9,207	$ 4,900	$ 9,207	$ 4,900		$ 15,654	$ 704	$ 15,654	$ 704
Senior Notes, interest rate, percentage			2.875%	5.875%	6.65%	6.875%	7.50%	7.20%	2.875%
Debt instrument expiration date				2016	2017	2018	2020	2028	2038