Significant Accounting Policies (Narrative) (Details)	Sep. 30, 2015
Four Brothers and Three Cedars
Subsidiary, Sale of Stock [Line Items]
Percentage ownership in total units	50.00%
Dominion Midstream Partners, LP
Subsidiary, Sale of Stock [Line Items]
Percentage ownership in total units	63.10%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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