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Regulatory Matters (Narrative) (Detail) customer in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Apr. 30, 2018 USD ($) customer | Feb. 28, 2018 USD ($) | Jun. 30, 2016 USD ($) | Apr. 30, 2016 | Aug. 31, 2009 kV | Apr. 30, 2008 | Apr. 30, 2007 kV | Mar. 31, 2018 USD ($) kV power_station mi | Dec. 31, 2017 USD ($)
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Regulatory assets-noncurrent |  |  |  |  |  |  |  |  | $ 2,698,000,000 | $ 2,480,000,000 | [1]
Regulatory asset recovered through retail rates |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Regulatory assets-noncurrent | [2] |  |  |  |  |  |  |  | 229,000,000 | 222,000,000 |
Virginia Regulation | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Charge associated with legislation |  |  |  |  |  |  |  |  | 215,000,000 |  |
Charge associated with legislation, after tax |  |  |  |  |  |  |  |  | 160,000,000 |  |
Virginia Electric and Power Company |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
ROE (percentage) |  |  |  |  |  |  | 11.40% |  |  |  |
Regulatory assets-noncurrent |  |  |  |  |  |  |  |  | 1,009,000,000 | 810,000,000 | [3]
Virginia Electric and Power Company | Regulatory asset recovered through retail rates |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Regulatory assets-noncurrent | [2] |  |  |  |  |  |  |  | $ 229,000,000 | 222,000,000 |
Virginia Electric and Power Company | Virginia Regulation |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Earnings above authorized return on equity (basis points) |  |  |  |  |  |  |  |  | 0.70% |  |
One-time bill credit, provisions for current customers |  |  |  |  |  |  |  |  | $ 200,000,000 |  |
Virginia Electric and Power Company | Virginia Regulation | Double Circuit Transmission Line Between Near Gainesville Substation And Haymarket Substation |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Capacity of transmission line (kV) | kV |  |  |  |  |  |  |  |  | 230 |  |
Length of kV line (miles) | mi |  |  |  |  |  |  |  |  | 5 |  |
Virginia Electric and Power Company | Virginia Regulation | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Charge associated with legislation |  |  |  |  |  |  |  |  | $ 215,000,000 |  |
Charge associated with legislation, after tax |  |  |  |  |  |  |  |  | 160,000,000 |  |
Reduction in base rate on annual basis |  |  |  |  |  |  |  |  | $ 125,000,000 |  |
Virginia Electric and Power Company | Virginia Regulation | Rider B |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
ROE (percentage) |  |  |  |  |  |  |  |  | 11.20% |  |
Number of power stations converted to biomass | power_station |  |  |  |  |  |  |  |  | 3 |  |
Approved revenue required |  |  | $ 47,000,000 |  |  |  |  |  |  |  |
Proposed revenue requirement |  |  |  |  |  |  |  |  | $ 42,000,000 |  |
Virginia Electric and Power Company | Virginia Regulation | Rider U |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Approved revenue required |  |  |  |  |  |  |  |  | 73,000,000 |  |
Phase of conversions |  |  |  |  |  |  |  |  | 179,000,000 |  |
Phase of conversions not previously approved for recovery |  |  |  |  |  |  |  |  | 65,000,000 |  |
Virginia Electric and Power Company | Settled Litigation | Federal Energy Regulatory Commission | Order Regarding Transmission Rate Design for Allocation of Costs among PJM Interconnect LLC Transmission Customers | Unfavorable Regulatory Action |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Amount required to pay under settlement agreement (in excess of $200 million) |  |  |  | $ 200,000,000 |  |  |  |  |  |  |
Duration of payment under settlement agreement |  |  |  | 10 years |  |  |  |  |  |  |
Amount of contingent liability |  |  |  |  |  |  |  |  | 239,000,000 |  |
Virginia Electric and Power Company | Settled Litigation | Federal Energy Regulatory Commission | Order Regarding Transmission Rate Design for Allocation of Costs among PJM Interconnect LLC Transmission Customers | Unfavorable Regulatory Action | Regulatory asset recovered through retail rates |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Regulatory assets-noncurrent |  |  |  |  |  |  |  |  | 229,000,000 |  |
Virginia Electric and Power Company | Minimum |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Facility operating capacity (kV) | kV |  |  |  |  |  |  |  | 500 |  |  |
Virginia Electric and Power Company | Minimum | Judicial Ruling |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Facility operating capacity (kV) | kV |  |  |  |  |  | 500 |  |  |  |  |
DETI | Federal Energy Regulatory Commission | Other operations and maintenance | Preliminary recommendation one |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Audit compliance charge recognized in connection with preliminary recommendation |  |  |  |  |  |  |  |  |  | 15,000,000 |
Audit compliance after-tax charge recognized in connection with preliminary recommendation |  |  |  |  |  |  |  |  |  | 9,000,000 |
DETI | Federal Energy Regulatory Commission | Other operations and maintenance | Other preliminary recommendation |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Audit compliance charge recognized in connection with preliminary recommendation |  |  |  |  |  |  |  |  |  | 0 |
Audit compliance after-tax charge recognized in connection with preliminary recommendation |  |  |  |  |  |  |  |  |  | 0 |
East Ohio | Ohio Regulation | Pipeline Infrastructure Replacement Program |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proposed revenue requirement |  |  |  |  |  |  |  |  | 165,000,000 |  |
Percentage replacement of pipeline system |  |  |  |  | 25.00% |  |  |  |  |  |
Total estimated cost |  |  |  |  |  |  |  |  | $ 1,400,000,000 | $ 204,000,000 |
East Ohio | Ohio Regulation | Automated Meter Reading Program |  |  |  |  |  |  |  |  |  |  |
Public Utilities General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proposed revenue requirement |  | $ 5,000,000 |  |  |  |  |  |  |  |  |
Number of customers with automated meter reading technology | customer |  | 1.2 |  |  |  |  |  |  |  |  |
[1] | Dominion Energy’s Consolidated Balance Sheet at December 31, 2017 has been derived from the audited Consolidated Balance Sheet at that date.
[2] | Reflects amounts related to the PJM transmission cost allocation matter. See Note 13 for more information.
[3] | Virginia Power’s Consolidated Balance Sheet at December 31, 2017 has been derived from the audited Consolidated Balance Sheet at that date.

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