Derivatives (Summary of Derivative Income Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 2,304	$ 1,006	$ 7,776
Loss on derivatives	2,304	1,006	7,776
Commodity Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Changes in fair value of derivatives that do not qualify for hedge accounting	1,674	(3,473)	726
Derivative, Gain (Loss) on Derivative, Net	633	4,514	7,015
Ineffective portion of derivatives qualifying for hedge accounting	(3)	(35)	(158)
Put Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Put option premium mark to market	0	0	193
Total Gain Loss on Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss on derivatives	$ 2,304	$ 1,006	$ 7,583