Derivative Financial Instruments (Derivatives And Hedging-Designated) (Details) (Designated As Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 2,798	$ 31
Liability Derivatives	2,008	6,457
NYMEX Commodity Contracts [Member] | Energy Commodity Derivatives Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	1,790	31
NYMEX Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	2,008	6,457
Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 1,008