Derivative Instruments And Hedging Activities (Impact Of Derivative Instruments On Accumulated Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	$ 30,043	[1]	$ (7,699)	$ (18,918)
Unrealized gains (losses)	(382)		(1,568)	5,237
Oil And Natural Gas Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	28,749	[1]	(6,486)	(19,092)
Unrealized gains (losses)	13,400
Foreign Exchange Forwards [Member]
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in OCI on Derivatives				(538)
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in OCI on Derivatives	1,294	[1]	(1,213)	712
Unrealized gains (losses)	$ (100)

[1] All unrealized gains (losses) related to our derivatives are expected to be reclassified into earnings by no later than December 31, 2014. The last of our interest rate swaps will be settled in January 2014. The last of our oil and natural gas commodity contracts will settle in December 2013. Most of our unrealized gain (losses) in OCI at December 31, 2011 is expected to be reclassified to earnings in 2012, including $13.4 million for our oil and natural gas contracts and $(0.1) million related to our interest swap contracts.