Fair Value (Details 2) (Commodity contracts, Significant unobservable inputs (Level 3))	9 Months Ended
	Sep. 30, 2013
Assets | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Crude option volatilities (as a percent)	16.37%
Assets | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Crude option volatilities (as a percent)	22.15%
Assets | Propane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.97
Assets | Propane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.07
Assets | Isobutane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.28
Assets | Isobutane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.41
Assets | Normal butane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.21
Assets | Normal butane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.38
Assets | Natural gasoline prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.93
Assets | Natural gasoline prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	2.07
Liabilities | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Propane option volatilities (as a percent)	14.01%
Crude option volatilities (as a percent)	11.61%
Liabilities | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Propane option volatilities (as a percent)	26.14%
Crude option volatilities (as a percent)	26.45%
Liabilities | Propane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.97
Liabilities | Propane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.07
Liabilities | Isobutane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.28
Liabilities | Isobutane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.40
Liabilities | Normal butane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.21
Liabilities | Normal butane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	1.37
Liabilities | Natural gasoline prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	2.03
Liabilities | Natural gasoline prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	2.07