Summary of Significant Accounting Policies, Derivatives by Hedging Relationship and Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified											3 Months Ended		9 Months Ended
	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Level 1 Quoted Prices [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Level 1 Quoted Prices [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Level 2 Observable [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Level 2 Observable [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Level 3 Unobservable [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Level 3 Unobservable [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Counterparty offsets [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Counterparty offsets [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Total Fair Value [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Total Fair Value [Member]	Sep. 30, 2012 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2011 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2012 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2011 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]
Earnings (loss) recognized in income [Abstract]
Earnings (Loss)											$ (1,562)	$ (3,236)	$ (2,555)	$ (2,728)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Forward Hydrocarbon Commodity Contracts - Current assets	0	1,455	4,267	2,045	0	0	(2,727)	(1,436)	1,540	2,064
Derivatives - Forward Hydrocarbon Commodity Contracts - Current liabilities	(1,391)	(675)	(4,048)	(1,442)	0	0	2,727	1,436	(2,712)	(681)
Net Value	$ (1,391)	$ 780	$ 219	$ 603	$ 0	$ 0	$ 0	$ 0	$ (1,172)	$ 1,383