Summary of Significant Accounting Policies, Derivatives by Hedging Relationship and Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified											3 Months Ended		6 Months Ended
	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Level 1 Quoted Prices [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 1 Quoted Prices [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Level 2 Observable [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 2 Observable [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Level 3 Unobservable [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 3 Unobservable [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Counterparty Offsets [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Counterparty Offsets [Member]	Jun. 30, 2014 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]	Jun. 30, 2013 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]	Jun. 30, 2014 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]	Jun. 30, 2013 Commodity Contract [Member] Revenues - marketing [Member] Not Designated as Hedging Instrument [Member]
Earnings (loss) recognized in income [Abstract]
Earnings (Loss)											$ (15)	$ (151)	$ 383	$ (1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - Current assets	176	395	0	0	176	449	0	0	0	(54)
Derivatives - Current liabilities	(112)	0	0	0	(112)	(54)	0	0	0	54
Net Value	$ 64	$ 395	$ 0	$ 0	$ 64	$ 395	$ 0	$ 0	$ 0	$ 0