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v3.19.3.a.u2

Investments (Investments Under Equity Method of Accounting) (Detail) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2019 | Feb. 25, 2020 | Dec. 31, 2018
Schedule of Equity Method Investments [Line Items] |  |  |
Investment Balance | $ 1,646 |  | $ 1,278
Atlantic Coast Pipeline |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% | 48.00% |  |
Investment Balance | $ 1,123 |  | 820
Description | Gas transmission system |  |
Iroquois |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% | 50.00% |  |
Investment Balance | $ 276 |  | 302
Description | Gas transmission system |  |
Fowler I Holdings LLC |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% | 50.00% |  |
Investment Balance | $ 74 |  | 82
Description | Wind-powered merchant generation facility |  |
Wrangler |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% | 20.00% |  |
Investment Balance | $ 77 |  | 0
Description | Nonregulated retail energy marketing |  |
Other Investment |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investment Balance | $ 96 |  | 74
Dominion Energy Gas Holdings, LLC |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Investment Balance | $ 312 |  | 339
Dominion Energy Gas Holdings, LLC | Atlantic Coast Pipeline |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% |  | 53.00% |
Dominion Energy Gas Holdings, LLC | Iroquois |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% | 50.00% |  |
Investment Balance | $ 276 |  | 302
Description | Gas transmission system |  |
Dominion Energy Gas Holdings, LLC | White Rive Hub |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership% | 50.00% |  |
Investment Balance | $ 36 |  | $ 37
Description | Gas transmission system |  |

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