Acquisitions and Dispositions (Schedule of Major Classes of Assets and Liabilities Reported As Held for Sale in Discontinued Operations) (Detail) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Current assets	[1]	$ 25	$ 1,482
Current liabilities			625
Dominion Energy Gas Holdings, LLC | Q-Pipe Group
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Current assets	[2]		47
Equity method investments	[3]		35
Property, plant and equipment, net			1,113
Other deferred charges and other assets, including goodwill and intangible assets	[4]		224
Current liabilities			30
Long-term debt			426
Other deferred credits and liabilities			$ 154

[1] See Note 9 for amounts attributable to related parties.

[2] Includes cash and cash equivalents of $7 million.

[3] Comprised of equity method investment in White River Hub.

[4] Includes goodwill of $191 million.