Derivative Financial Instruments (Derivatives and Hedging-Cash Flow Hedge) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Amount of Gain Recognized in AOCL on Derivative	$ 4,613		$ 4,613	$ (289)
Amount of Gain Reclassified from AOCL into Income	41		82	(1,953)
Interest Rate Swap Agreements [Member]
Amount of Gain Recognized in AOCL on Derivative
Interest Rate Swap Agreements [Member] | Interest Expense [Member]
Amount of Gain Reclassified from AOCL into Income	41	41	82	82
NYMEX Commodity Contracts [Member]
Amount of Gain Recognized in AOCL on Derivative	4,613		4,613	(289)
NYMEX Commodity Contracts [Member] | Product Sales Revenue [Member]
Amount of Gain Reclassified from AOCL into Income				$ (2,035)