Derivative Financial Instruments (Derivatives And Hedging-Overall-Subsequent Measurement) (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 3,332	$ (4,428)
NYMEX Commodity Contracts [Member] | Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2,823	(1,761)
NYMEX Commodity Contracts [Member] | Operating Expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	365	(1,886)
Butane Futures Agreements [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 144	$ (781)