Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Mar. 31, 2025	Dec. 31, 2024
Derivatives Fair Value [Line Items]
Total current derivative assets	[1]	$ 251	$ 436
Total noncurrent derivative assets	[2]	813	963
Total derivative assets		1,064	1,399
Total current derivative liabilities	[1]	207	207
Total noncurrent derivative liabilities	[2]	268	305
Total derivative liabilities		475	512
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Total current derivative assets	[1]	54	248
Total noncurrent derivative assets	[2]	58	127
Total derivative assets		112	375
Total current derivative liabilities	[1]	122	139
Total noncurrent derivative liabilities	[2]	61	86
Total derivative liabilities		183	225
Designated as Hedging Instrument | Interest Rate Contract
Derivatives Fair Value [Line Items]
Total current derivative assets		5	137
Total noncurrent derivative assets		35	93
Total current derivative liabilities		0	0
Total noncurrent derivative liabilities		30	0
Designated as Hedging Instrument | Interest Rate Contract | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Total current derivative assets		5	137
Total noncurrent derivative assets		35	93
Total current derivative liabilities		0	0
Total noncurrent derivative liabilities		17	0
Fair Value - Derivatives not under Hedge Accounting | Commodity Contract
Derivatives Fair Value [Line Items]
Total current derivative assets		145	171
Total noncurrent derivative assets		256	323
Total current derivative liabilities		117	78
Total noncurrent derivative liabilities		33	45
Fair Value - Derivatives not under Hedge Accounting | Commodity Contract | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Total current derivative assets		40	84
Total noncurrent derivative assets		23	31
Total current derivative liabilities		44	32
Total noncurrent derivative liabilities		1	1
Fair Value - Derivatives not under Hedge Accounting | Interest Rate Contract
Derivatives Fair Value [Line Items]
Total current derivative assets		92	101
Total noncurrent derivative assets		522	544
Total current derivative liabilities		12	22
Total noncurrent derivative liabilities		162	175
Fair Value - Derivatives not under Hedge Accounting | Foreign currency exchange rate
Derivatives Fair Value [Line Items]
Total current derivative assets		9	27
Total noncurrent derivative assets		0	3
Total current derivative liabilities		78	107
Total noncurrent derivative liabilities		43	85
Fair Value - Derivatives not under Hedge Accounting | Foreign currency exchange rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Total current derivative assets		9	27
Total noncurrent derivative assets		0	3
Total current derivative liabilities		78	107
Total noncurrent derivative liabilities		$ 43	$ 85

[1] Current derivative liabilities are presented in other current liabilities in the Companies’ Consolidated Balance Sheets.

[2] Noncurrent derivative assets are presented in other deferred charges and other assets and noncurrent derivative liabilities are presented in other deferred credits and other liabilities in the Companies’ Consolidated Balance Sheets.