Acquisitions and Dispositions (Tables)	12 Months Ended
Dec. 31, 2013
Noble JV [Member]
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Information
Dominion Acquisition Member
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Information	.

Tabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregate.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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