Derivative Financial Instruments Derivative Financial Instruments (Schedule of Marketing Derivative Contracts Volume and Weighted Average Prices) (Details) (Details) - Jun. 30, 2015 - Subsequent Event Type [Domain] - Basis Swap Contracts for Current Year [Member]	MMBTU / d $ / bbl
Marketing Oil contracts, in BBL [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	10,000
Marketing oil contracts, price per BBL [Member] [Member]
Derivative [Line Items]
Derivative, Swap Type, Average Fixed Price | $ / bbl	2.99