Fair Value (Details 2) - Commodity contracts - Significant unobservable inputs (Level 3)	Sep. 30, 2015 $ / item
Liability | Ethane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.20
Liability | Ethane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.20
Liability | Propane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.46
Liability | Propane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.50
Liability | Normal butane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.62
Liability | Normal butane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.62
Asset | Ethane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.20
Asset | Ethane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.21
Asset | Propane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.46
Asset | Propane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.48
Asset | Isobutane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.61
Asset | Isobutane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.64
Asset | Normal butane prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.56
Asset | Normal butane prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.62
Asset | Natural gasoline prices | Minimum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.94
Asset | Natural gasoline prices | Maximum
Unobservable inputs used in the valuation of Level 3 instruments of Assets and Liabilities
Forward price (in dollars per unit)	0.99