Equity (Narrative) (Detail)	1 Months Ended													3 Months Ended					12 Months Ended
	Dec. 31, 2021 USD ($) shares	Nov. 30, 2021 $ / shares shares	Aug. 31, 2021 USD ($) shares	Jul. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Nov. 30, 2020 USD ($) shares	Sep. 30, 2020 USD ($) agreement shares	Aug. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Oct. 31, 2019	Aug. 31, 2019 USD ($) shares	Jan. 31, 2019 USD ($) shares	Dec. 31, 2020 USD ($) shares	Sep. 30, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Mar. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Jul. 31, 2020 USD ($)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock												$ 1,400,000,000							$ 192,000,000	$ 159,000,000	$ 2,515,000,000
Issuance of common stock (in shares) | shares			600,000	1,400,000			4,100,000					18,500,000									6,100,000
Acquisition of SCANA																					$ 6,818,000,000
Amount of income taxes recognized in equity primarily attributable to establishing additional regulatory liabilities																					(40,000,000)
Issuance of common stock value			$ 45,000,000	$ 104,000,000															1,332,000,000	481,000,000	5,401,000,000
Fees and commissions paid																					28,000,000
Stock repurchased, shares | shares							4,100,000
Stock repurchased, value							$ 323,000,000													3,080,000,000
Number of prepaid accelerated share repurchase agreements | agreement							2
Accelerated share repurchase, payments					$ 400,000,000		$ 1,500,000,000							$ 400,000,000	$ 1,500,000,000					$ 400,000,000
Accelerated share repurchase, cash paid for number of shares exchange | shares					5,000,000.0		17,200,000							5,000,000.0	17,200,000					5,000,000.0
Decrease in common stock					$ 400,000,000	$ 1,500,000,000
Common stock worth based on closing Price					$ 400,000,000		$ 1,500,000,000							$ 400,000,000	$ 1,500,000,000					$ 400,000,000
Accelerated share repurchase, additional shares delivered under terms of the agreement | shares					300,000	1,400,000								300,000						300,000
Compensation cost related to stock-based compensation																			42,000,000	$ 64,000,000	46,000,000
Tax benefit from stock awards and stock options exercised																			$ 9,000,000	16,000,000	11,000,000
Vesting period																			3 years
Cash Based Performance Grant | Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Cash-based performance grants minimum percentage																			0.00%
Cash-based performance grants maximum percentage																			200.00%
February2019 Cash Based Performance Grant | Officer | Grant Date Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Targeted amount of the grant	$ 5,700,000																		$ 5,700,000
February 2020 Cash Based Performance Grant | Officer | Grant Date Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Targeted amount of the grant	10,000,000																		10,000,000
Liability accrued for award	6,000,000																		6,000,000
February 2021 Cash Based Performance Grant | Officer | Grant Date Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Targeted amount of the grant	13,000,000																		13,000,000
Liability accrued for award	$ 4,000,000																		$ 4,000,000
Stock Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares were available for future grants | shares	19,000,000																		19,000,000
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested awards	$ 55,000,000																		$ 55,000,000
Fair value of restricted stock awards that vested																			$ 37,000,000	$ 35,000,000	$ 23,000,000
Cove Point
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership interest percentage of limited partner interests						100.00%				25.00%	25.00%
Cash consideration from sale of noncontrolling interest										$ 2,100,000,000
Cove Point | GT&S Transaction
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Controlling interest sold						25.00%
Ownership percentage						50.00%
Reversal of noncontrolling interest held by noncontrolling owners						$ 1,400,000,000
S B L Holdco L L C | Nonregulated Solar Projects
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Controlling interest sold	67.00%
Four Brothers And Three Cedars
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Controlling interest sold	50.00%
Maximum | Stock Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum term of stock based awards																			8 years
Weighted Average | Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected weighted-average period recognized for the unrecognized compensation cost																			2 years
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (in shares) | shares																			4,000,000	7,000,000	39,000,000
Acquisition of SCANA (in shares) | shares																					96,000,000
Acquisition of SCANA																					$ 6,818,000,000
Amount of income taxes recognized in equity primarily attributable to establishing additional regulatory liabilities																					1,181,000,000
Defined Benefit Pension plans																					499,000,000
Issuance of common stock value																			$ 340,000,000	$ 481,000,000	3,014,000,000
Fees and commissions paid																					$ 14,000,000
Stock repurchased, shares | shares																			0	38,900,000	0
Stock repurchased, value						$ 1,000,000,000.0														$ 3,080,000,000
Stock repurchase program, authorized amount																						$ 3,000,000,000.0
Common Stock | Open Market Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock repurchased, shares | shares														3,700,000	7,200,000
Stock repurchased, value														$ 295,000,000	$ 562,000,000
Dominion Energy Midstream Partners, LP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Acquisition of SCANA (in shares) | shares													22,500,000
Acquisition of SCANA													$ 1,600,000,000
Common units conversion ratio													0.2492
Gain or loss recognized in equity transaction													$ 0
Amount of income taxes recognized in equity primarily attributable to establishing additional regulatory liabilities													$ 40,000,000
Dominion Energy Direct
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock																			$ 192,000,000	$ 159,000,000
Issuance of common stock (in shares) | shares																			2,600,000	2,100,000
SCANA
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Acquisition of SCANA (in shares) | shares													95,600,000								95,600,000
Acquisition of SCANA													$ 6,800,000,000								$ 6,800,000,000
Various Programs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock																			$ 340,000,000	$ 481,000,000	$ 11,000,000,000.0
Issuance of common stock (in shares) | shares																			4,000,000	7,000,000	157,000,000
Sales Agency Agreements to Effect Sales Under At-the-market Program
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock																$ 639,000,000	$ 154,000,000	$ 197,000,000
Issuance of common stock (in shares) | shares									0							7,800,000	2,100,000	2,700,000
Fees and commissions paid																$ 6,000,000	$ 2,000,000	$ 2,000,000
Sale of stock authorized amount									$ 500,000,000
Sales Agency Agreements to Effect Sales Under At-the-market Program | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale of stock authorized amount								$ 1,000,000,000.0
Forward Sale Agreements
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Forward sale agreements, number of shares of common stock to be settled | shares		1,100,000
Initial forward price of share | $ / shares		$ 74.66