Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Detail) - USD ($) $ in Millions		Dec. 31, 2019		Dec. 31, 2018
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		$ 497		$ 356
Regulatory liabilities-noncurrent		11,001		6,840
Total regulatory liabilities		11,498		7,196
Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		167		299
Regulatory liabilities-noncurrent		5,074		4,647
Total regulatory liabilities		5,241		4,946
Dominion Energy Gas Holdings, LLC
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[1]	41		24
Regulatory liabilities-noncurrent		800		765
Total regulatory liabilities		841		789
Provision for future cost of removal and AROs
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[2]	142		117
Regulatory liabilities-noncurrent	[2]	2,302		1,409
Provision for future cost of removal and AROs | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[3]	103		92
Provision for future cost of removal and AROs | Dominion Energy Gas Holdings, LLC
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[4]	18		9
Regulatory liabilities-noncurrent	[1]	95		113
Reserve for refunds and rate credits to electric utility customers
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[5]	143		71
Regulatory liabilities-noncurrent	[5]	656
Reserve for refunds and rate credits to electric utility customers | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[6]			71
Cost-of-service impact of 2017 Tax Reform Act
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[7]	4		104
Cost-of-service impact of 2017 Tax Reform Act | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[8]			95
Income taxes refundable through future rates
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		77	[9]	0
Regulatory liabilities-noncurrent	[9]	5,088		4,071
Income taxes refundable through future rates | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		54	[10]	0
Regulatory liabilities-noncurrent	[10]	2,438		2,579
Income taxes refundable through future rates | Dominion Energy Gas Holdings, LLC
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[11]	560		530
Monetization of guarantee settlement
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		67	[12]	0
Regulatory liabilities-noncurrent		970	[12]	0
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		64		64
Regulatory liabilities-noncurrent		325		170
Other | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		10		41
Regulatory liabilities-noncurrent		111		58
Other | Dominion Energy Gas Holdings, LLC
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		15		8
Regulatory liabilities-noncurrent		12		16
Nuclear decommissioning trust
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[13]	1,471		1,070
Nuclear decommissioning trust | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[14]	1,471		1,070
Overrecovered other postretirement benefit costs
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[15]	189		120
Overrecovered other postretirement benefit costs | Dominion Energy Gas Holdings, LLC
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[16]	133		106
Provision for future cost of removal | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[3]	1,054		940
Overrecovered gas costs | Dominion Energy Gas Holdings, LLC
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[17]	$ 8		$ 7

[1] Current regulatory liabilities are presented in other current liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.

[2] Rates charged to customers by Dominion Energy’s regulated businesses include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.

[3] Rates charged to customers by Virginia Power’s regulated businesses include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.

[4] Rates charged to customers by Dominion Energy Gas’ regulated businesses include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement.

[5] Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited over an estimated 11-year period in connection with the SCANA Merger Approval Order and Virginia legislation enacted in March 2018 that required one-time rate credits of certain amounts to utility customers in Virginia. See Notes 3 and 13 for additional information.

[6] Charge associated with Virginia legislation enacted in March 2018 that required one-time rate credits of certain amounts to utility customers. See Note 13 for additional information.

[7] Balance refundable to customers related to the decrease in revenue requirements for recovery of income taxes at the Companies’ regulated electric generation and electric and natural gas distribution operations. See Notes 3 and 13 for additional information.

[8] Balance refundable to customers related to the decrease in revenue requirements for recovery of income taxes at regulated electric generation and distribution operations. See Note 13 for additional information.

[9] Amounts recorded to pass the effect of reduced income taxes from the 2017 Tax Reform Act to customers in future periods, which will reverse at the weighted average tax rate that was used to build the reserves over the remaining book life of the property, net of amounts to be recovered through future rates to pay income taxes that become payable when rate revenue is provided to recover AFUDC equity.

[10] Amounts recorded to pass the effect of reduced income taxes from the 2017 Tax Reform Act to customers in future periods, which will reverse at the weighted average tax rate that was used to build the reserves over the remaining book life of the property, net of amounts to be recovered through future rates to pay income taxes that become payable when rate revenue is provided to recover AFUDC equity.

[11] Amounts recorded to pass the effect of reduced income taxes from the 2017 Tax Reform Act to customers in future periods, which will reverse at the weighted average tax rate that was used to build the reserves over the remaining book life of the property, net of amounts to be recovered through future rates to pay income taxes that become payable when rate revenue is provided to recover AFUDC equity.

[12] Reflects amounts to be refunded to DESC electric service customers over a 20-year period ending in 2039 associated with the monetization of a bankruptcy settlement agreement. See Note 3 for additional information.

[13] Primarily reflects a regulatory liability representing amounts collected from Virginia jurisdictional customers and placed in external trusts (including income, losses and changes in fair value thereon, as applicable) for the future decommissioning of Dominion Energy’s utility nuclear generation stations, in excess of the related AROs.

[14] Primarily reflects a regulatory liability representing amounts collected from Virginia jurisdictional customers and placed in external trusts (including income, losses and changes in fair value thereon) for the future decommissioning of Virginia Power’s utility nuclear generation stations, in excess of the related AROs.

[15] Reflects a regulatory liability for the collection of postretirement benefit costs allowed in rates in excess of expense incurred.

[16] Reflects a regulatory liability for the collection of postretirement benefit costs allowed in rates in excess of expense incurred.

[17] Reflects unrecovered or overrecovered gas costs at regulated gas operations, which are recovered or refunded through filings with the applicable regulatory authority.