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Property, Plant and Equipment (Share of Jointly-Owned Power Stations) (Detail) $ in Millions | Dec. 31, 2017 USD ($)
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Millstone Unit [Member] |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership interest | 93.50% | [1]
Plant in service | $ 1,217 | [1]
Accumulated depreciation | (381) | [1]
Nuclear fuel | 552 | [1]
Accumulated amortization of nuclear fuel | (427) | [1]
Plant under construction | $ 68 | [1]
Virginia Electric and Power Company | Bath Country Pumped Storage Station [Member] |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership interest | 60.00% | [2]
Plant in service | $ 1,059 | [2]
Accumulated depreciation | (612) | [2]
Plant under construction | $ 2 | [2]
Virginia Electric and Power Company | North Anna |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership interest | 88.40% | [2]
Plant in service | $ 2,504 | [2]
Accumulated depreciation | (1,263) | [2]
Nuclear fuel | 745 | [2]
Accumulated amortization of nuclear fuel | (607) | [2]
Plant under construction | $ 92 | [2]
Virginia Electric and Power Company | Clover Power Station [Member] |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Ownership interest | 50.00% | [2]
Plant in service | $ 589 | [2]
Accumulated depreciation | (231) | [2]
Plant under construction | $ 6 | [2]
[1] | Unit jointly owned by Dominion Energy.
[2] | Units jointly owned by Virginia Power.

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- Definition Jointly Owned Utility Plant Nuclear Fuel + References No definition available. + Details
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- Definition The period end amount owned by the reporting utility of a jointly owned utility plant in service. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033 + Details
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- Definition 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. + References No definition available. + Details
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- Definition The period end amount of construction work in progress at a jointly owned electricity generation plant. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033 + Details
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- Definition The period end amount of accumulated depreciation in a jointly owned electricity generation plant. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033 + Details
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- Definition The proportionate share of interest (percent) in a jointly owned utility plant. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033 + Details
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