Leases (Lease Assets and Liabilities Recorded in Consolidated Balance Sheets) (Detail) - USD ($) $ in Millions		Dec. 31, 2021		Dec. 31, 2020		Jan. 01, 2019
Lessee Lease Disclosure [Line Items]
Operating lease assets		$ 506	[1]	$ 564	[1]	$ 504
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		us-gaap:PrepaidExpenseAndOtherAssetsNoncurrent		us-gaap:PrepaidExpenseAndOtherAssetsNoncurrent
Finance lease assets	[2]	$ 144		$ 148
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		Property, plant and equipment		Property, plant and equipment
Total lease assets		$ 650		$ 712
Operating lease liabilities	[3]	$ 44		$ 54
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Other		Other
Finance lease liabilities	[4]	$ 36		$ 32
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Securities due within one year		Securities due within one year
Total lease liabilities - current		$ 80		$ 86
Operating lease liabilities	[5]	$ 464		$ 516
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Deferred Credits And Other Liabilities		Deferred Credits And Other Liabilities
Finance lease liabilities	[6]	$ 112		$ 108
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Other		Other
Total lease liabilities - noncurrent		$ 576		$ 624
Total lease liabilities		656		710
Virginia Electric and Power Company
Lessee Lease Disclosure [Line Items]
Operating lease assets		$ 256	[1]	$ 185	[1]	$ 209
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		us-gaap:PrepaidExpenseAndOtherAssetsNoncurrent		us-gaap:PrepaidExpenseAndOtherAssetsNoncurrent
Finance lease assets	[2]	$ 71		$ 45
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		Property, plant and equipment		Property, plant and equipment
Total lease assets		$ 327		$ 230
Operating lease liabilities	[3]	$ 25		$ 28
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Other		Other
Finance lease liabilities	[4]	$ 13		$ 8
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Securities due within one year		Securities due within one year
Total lease liabilities - current		$ 38		$ 36
Operating lease liabilities	[5]	$ 227		$ 155
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Deferred Credits And Other Liabilities		Deferred Credits And Other Liabilities
Finance lease liabilities	[6]	$ 57		$ 36
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Other		Other
Total lease liabilities - noncurrent		$ 284		$ 191
Total lease liabilities		$ 322		$ 227

[1] Included in other deferred charges and other assets in the Companies’ Consolidated Balance Sheets.

[2] Included in property, plant and equipment in the Companies’ Consolidated Balance Sheets, net of $81 million and $18 million of accumulated amortization at Dominion Energy and Virginia Power, respectively, at December 31, 2021 and net of $50 million and $9 million of accumulated amortization at Dominion Energy and Virginia Power, respectively, at December 31, 2020.

[3] Included in other current liabilities in the Companies’ Consolidated Balance Sheets.

[4] Included in securities due within one year in the Companies’ Consolidated Balance Sheets.

[5] Included in other deferred credits and other liabilities in the Companies’ Consolidated Balance Sheets.

[6] Included in other long-term debt in the Companies’ Consolidated Balance Sheets.