Derivative Instruments And Hedging Activities (Impact Of Non-Designated Derivative Instruments On Income Statement) (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 Income on Derivatives	$ 249	$ (1,472)	$ 92,296
Natural Gas Contracts [Member] | Gain On Oil And Gas Derivative Contracts [Member]
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in Income on Derivatives		1,088	89,485
Interest Rate Swaps [Member] | Other Income (Expense) [Member]
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in Income on Derivatives			(468)
Foreign Exchange Forwards [Member] | Other Income (Expense) [Member]
Derivatives, Fair Value [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ 249	$ (2,560)	$ 3,279