Financial Instruments and Concentrations of Risk (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Fair Value of Financial Assets and Liabilities
Total assets	$ 0		$ 0
Total liabilities	58,194		33,892
Derivative, Fair Value, Net	(58,194)		(33,892)
Level 1 [Member]
Fair Value of Financial Assets and Liabilities
Total assets	36		22
Total liabilities	58,230		33,914
Derivative, Fair Value, Net	(58,194)		(33,892)
Netting [Member]
Fair Value of Financial Assets and Liabilities
Total assets	(36)	[1]	(22)	[1]
Total liabilities	(36)	[1]	(22)	[1]
Derivative, Fair Value, Net	0	[1]	0	[1]
Commodity Derivatives [Member]
Fair Value of Financial Assets and Liabilities
Total assets	0		0
Total liabilities	60		1,034
Commodity Derivatives [Member] | Level 1 [Member]
Fair Value of Financial Assets and Liabilities
Total assets	36		22
Total liabilities	96		1,056
Commodity Derivatives [Member] | Netting [Member]
Fair Value of Financial Assets and Liabilities
Total assets	(36)	[1]	(22)	[1]
Total liabilities	(36)	[1]	(22)	[1]
Warrants [Member]
Fair Value of Financial Assets and Liabilities
Total liabilities	58,134		32,858
Warrants [Member] | Level 1 [Member]
Fair Value of Financial Assets and Liabilities
Total liabilities	58,134		32,858
Warrants [Member] | Netting [Member]
Fair Value of Financial Assets and Liabilities
Total liabilities			$ 0

[1] Relates primarily to exchange traded futures. Gain and loss positions on multiple contracts are settled net on a daily basis with the exchange.