Acquisitions and Dispositions (Schedule of Capital Expenditures and Significant Noncash Items Reported As Discontinued Operations) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Significant noncash items
Charges related to a voluntary retirement program				$ 320
Depreciation, depletion and amortization		$ 2,332		2,283	$ 1,660
Accrued capital expenditures	[1],[2],[3],[4],[5]	485		555	307
Dominion Energy Gas Holdings, LLC | GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Capital expenditures		292	[6]	386	728
Significant noncash items
Impairment of assets and other charges		469	[6]	13	391
Charges related to a voluntary retirement program		0	[6]	19	0
Depreciation, depletion and amortization		177	[6]	322	283
Accrued capital expenditures		0	[6]	25	56
Dominion Energy Gas Holdings, LLC | Q-Pipe Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Capital expenditures		38		42	34
Significant noncash items
Impairment of assets and other charges		0		1	0
Charges related to a voluntary retirement program		0		3	0
Depreciation, depletion and amortization		27		51	57
Accrued capital expenditures		$ 1		$ 2	$ 2

[1] See Note 3 for noncash investing and financing activities related to the SCANA Combination.

[2] See Note 5 for noncash activities related to the sale of a noncontrolling interest in Cove Point.

[3] See Note 9 for noncash investing activities related to the acquisition of a noncontrolling interest in Wrangler.

[4] See Notes 18,19 and 20 for noncash financing activities related to the acquisition of the public interest in Dominion Energy Midstream, the remarketing of RSNs, the issuance of stock purchase contracts associated with the 2019 Equity Units, the contribution of stock to Dominion Energy’s qualified defined benefit pension plan, derivative restructuring and the issuance of common stock associated with the settlement of litigation. See Note 23 for non-cash investing activities related to property, plant and equipment conveyed to satisfy litigation.

[5] See the New Accounting Standards section below for noncash investing and financing activities related to the adoption of a new accounting standard for leasing arrangements.

[6] Operations associated with the GT&S Transaction are through the November 1, 2020 settlement date.