Fair Value (Details 3) (Embedded Derivatives in Commodity contracts, Significant unobservable inputs (Level 3))	3 Months Ended
	Mar. 31, 2014 period
Assets | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward ERCOT Pricing (per Megawatt Hour)	36.36
Assets | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward ERCOT Pricing (per Megawatt Hour)	71.77
Liabilities
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Number of renewal periods	2
Term of counterparty option to renew gas purchase agreement	5 years
Probability of renewal (as a percent)	0.00%
Propane prices | Liabilities | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	0.94
Propane prices | Liabilities | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	1.10
Isobutane prices | Liabilities | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	1.17
Isobutane prices | Liabilities | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	1.32
Normal butane prices | Liabilities | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	1.08
Normal butane prices | Liabilities | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	1.28
Natural gasoline prices | Liabilities | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	1.72
Natural gasoline prices | Liabilities | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	2.17
Natural gas prices | Liabilities | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	3.52
Natural gas prices | Liabilities | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets
Forward price (in dollars per unit)	4.93