Derivative Financial Instruments Derivative Financial Instruments (Schedule of NGL Derivative Contracts Volume and Weighted Average Prices) (Details)	Sep. 30, 2015 bbl / d $ / bbl
Propane [Member] | NGL contract, in BBLS [Member] | Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	11,000
Propane [Member] | NGL contract, in BBLS [Member] | Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	7,500
Propane [Member] | NGL contracts, price per BBL [Member] | Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	21.62
Propane [Member] | NGL contracts, price per BBL [Member] | Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	21.57
Ethane [Member] | NGL contract, in BBLS [Member] | Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	6,000
Ethane [Member] | NGL contract, in BBLS [Member] | Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | bbl / d	5,000
Ethane [Member] | NGL contracts, price per BBL [Member] | Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	7.80
Ethane [Member] | NGL contracts, price per BBL [Member] | Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	11.61