Derivative Contracts (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2012
Derivative [Line Items]
Maximum Forecasted Production Covered By Derivatives	100.00%
Expected Annual Production Covered By Derivatives	50.00%
Term Loan due 2017 [Member]
Derivative [Line Items]
Line of Credit Maximum Borrowing Capacity		$ 600.0
First Term Loan Tranche [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount			$ 300.0
Derivative, Fixed Interest Rate			1.07%
Second Term Loan Tranche [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount		$ 300.0
Derivative, Fixed Interest Rate		0.86%