Derivative Financial Instruments Derivative Financial Instruments (Schedule of Marketing Derivative Contracts Volume and Weighted Average Prices) (Details) (Details)	Sep. 30, 2014
Marketing Gas contracts, in MMBTU [Member] | Basis Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	40,000
Marketing gas contracts, price per MMBTU [Member] | Basis Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	0.31
Marketing Oil contracts, in BBL [Member] | Basis Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	10,000
Marketing Oil contracts, in BBL [Member] | Basis Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	10,000
Marketing oil contracts, price per BBL [Member] [Member] | Basis Swap Contracts for Current Year [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	2.81
Marketing oil contracts, price per BBL [Member] [Member] | Basis Swap Contracts for Year 2 [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price	2.99