Derivative Contracts (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Forecasted production from proved reserves (in hundredths)	100.00%
Term Loan due 2017 [Member]
Derivatives, Fair Value [Line Items]
Total principal amount of debt		$ 600.0
Effective interest Rate Before Impact of Derivatives	3.24%
First Term Loan Tranche [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional amount of interest rate derivatives	300.0
Fixed Rate Paid (in hundredths)	1.07%
Second Term Loan Tranche [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional amount of interest rate derivatives	300.0
Fixed Rate Paid (in hundredths)	0.86%

Effective interest Rate Before Impact of Derivatives

No definition available.

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- Definition

Potential maximum amount of forecasted production covered by derivative contracts.

+ References

No definition available.

+ Details

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

+ Details

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- Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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- Details

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- Details

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