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Related-Party Transactions (Parenthetical) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Related Party Transaction [Line Items] |  |  |
Capital expenditures | $ 5,504 | $ 6,085 | $ 5,575
Virginia Electric and Power Company |  |  |
Related Party Transaction [Line Items] |  |  |
Capital expenditures | 2,496 | 2,489 | 2,474
Virginia Electric and Power Company | Services provided by affiliates | Affiliated Entity |  |  |
Related Party Transaction [Line Items] |  |  |
Capital expenditures | 144 | 144 | 143
Dominion Energy Gas Holdings, LLC |  |  |
Related Party Transaction [Line Items] |  |  |
Capital expenditures | 778 | 854 | 795
Dominion Energy Gas Holdings, LLC | Services provided by affiliates | Affiliated Entity |  |  |
Related Party Transaction [Line Items] |  |  |
Capital expenditures | $ 45 | $ 49 | $ 57

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- Definition The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
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- Details
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