Fair Value Measurements (Narrative) (Details) (Commodity Option [Member])	3 Months Ended
Mar. 31, 2015
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assumptions, Expected Volatility Rate	26.00%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Assumptions, Expected Volatility Rate	73.00%

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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