Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Fair Value of Financial Assets and Liabilities
Total assets	$ 725
Total liabilities	46,350		33,892
Net assets (liabilities) at fair value	(45,625)		(33,892)
Level 1 [Member]
Fair Value of Financial Assets and Liabilities
Total assets	857		22
Total liabilities	46,482		33,914
Net assets (liabilities) at fair value	(45,625)		(33,892)
Netting [Member]
Fair Value of Financial Assets and Liabilities
Total assets	(132)	[1]	(22)	[1]
Total liabilities	(132)	[1]	(22)	[1]
Net assets (liabilities) at fair value		[1]		[1]
Commodity Derivatives [Member]
Fair Value of Financial Assets and Liabilities
Total assets	725		0
Total liabilities	0		1,034
Commodity Derivatives [Member] | Level 1 [Member]
Fair Value of Financial Assets and Liabilities
Total assets	857		22
Total liabilities	132		1,056
Commodity Derivatives [Member] | Netting [Member]
Fair Value of Financial Assets and Liabilities
Total assets	(132)	[1]	(22)	[1]
Total liabilities	(132)	[1]	(22)	[1]
Warrants [Member]
Fair Value of Financial Assets and Liabilities
Total liabilities	46,350		32,858
Warrants [Member] | Level 1 [Member]
Fair Value of Financial Assets and Liabilities
Total liabilities	46,350		32,858
Warrants [Member] | Netting [Member]
Fair Value of Financial Assets and Liabilities
Total liabilities		[1]		[1]

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