Fair Value Measurements (Assets and Liabilities that are Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	$ 210
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	4,325		4,192
Total liabilities	941		1,157
Fair Value, Measurements, Recurring | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	1,007		965
Derivative Liabilities	620		888
Fair Value, Measurements, Recurring | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	104		105
Derivative Liabilities	321		269
Fair Value, Measurements, Recurring | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,865	[1]	1,718	[1]
Fair Value, Measurements, Recurring | Equity Securities | Large cap | Non United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10	[1]	10	[1]
Fair Value, Measurements, Recurring | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	55	[1]	51	[1]
Fair Value, Measurements, Recurring | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	299	[1]	332	[1]
Fair Value, Measurements, Recurring | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	458	[1]	458	[1]
Fair Value, Measurements, Recurring | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	360	[1]	329	[1]
Fair Value, Measurements, Recurring | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	19	[1]	23	[1]
Fair Value, Measurements, Recurring | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	78	[1]	60	[1]
Fair Value, Measurements, Recurring | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	70	[1]	141	[1]
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,254		2,100
Total liabilities	10		10
Fair Value, Measurements, Recurring | Level 1 | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	26		44
Derivative Liabilities	10		10
Fair Value, Measurements, Recurring | Level 1 | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0		0
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring | Level 1 | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,865	[1]	1,718	[1]
Fair Value, Measurements, Recurring | Level 1 | Equity Securities | Large cap | Non United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10	[1]	10	[1]
Fair Value, Measurements, Recurring | Level 1 | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	55	[1]	51	[1]
Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	298	[1]	277	[1]
Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 1 | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 1 | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,861		1,999
Total liabilities	876		983
Fair Value, Measurements, Recurring | Level 2 | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	771		828
Derivative Liabilities	555		714
Fair Value, Measurements, Recurring | Level 2 | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	104		105
Derivative Liabilities	321		269
Fair Value, Measurements, Recurring | Level 2 | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 2 | Equity Securities | Large cap | Non United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 2 | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	299	[1]	332	[1]
Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	160	[1]	181	[1]
Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	360	[1]	329	[1]
Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	19	[1]	23	[1]
Fair Value, Measurements, Recurring | Level 2 | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	78	[1]	60	[1]
Fair Value, Measurements, Recurring | Level 2 | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	70	[1]	141	[1]
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	210		93
Total liabilities	55		164
Fair Value, Measurements, Recurring | Level 3 | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	210		93
Derivative Liabilities	55		164
Fair Value, Measurements, Recurring | Level 3 | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0		0
Derivative Liabilities	0		0
Fair Value, Measurements, Recurring | Level 3 | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Equity Securities | Large cap | Non United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Fair Value, Measurements, Recurring | Level 3 | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,341		1,301
Total liabilities	116		147
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	5		2
Derivative Liabilities	11		47
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	105		100
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	737	[1]	679	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	24	[1]	23	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	180	[1]	214	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	187	[1]	170	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	148	[1]	125	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	14	[1]	16	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	35	[1]	40	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	11	[1]	32	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	877		809
Total liabilities	0		0
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0		0
Derivative Liabilities	0		0
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	0		0
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	737	[1]	679	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	24	[1]	23	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	116	[1]	107	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 1 | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	460		490
Total liabilities	113		117
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	1		0
Derivative Liabilities	8		17
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	105		100
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	180	[1]	214	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	71	[1]	63	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	148	[1]	125	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	14	[1]	16	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	35	[1]	40	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 2 | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	11	[1]	32	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	4		2
Total liabilities	3		30
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	4		2
Derivative Liabilities	3		30
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Interest Rate Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities	0		0
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Equity Securities | Large cap | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Equity Securities | Equity securities, other | United States
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | U.S. Treasury securities and agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities | Debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Cash equivalents and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	[1]	0	[1]
Virginia Electric and Power Company | Fair Value, Measurements, Recurring | Level 3 | Restricted cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 0	[1]	$ 0	[1]

[1] Includes investments held in the nuclear decommissioning and rabbi trusts.