Derivatives and Hedge Accounting Activities (Volume of our Derivative Activity) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Current
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate	$ 1,500
Current | Natural Gas (bcf): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	249,000,000,000	[1]
Current | Natural Gas (bcf): | Basis
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	786,000,000,000	[1]
Current | Electricity (MWh): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	20,100,938	[1]
Current | Electricity (MWh): | FTRs
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	46,851,683
Current | Capacity (MW)
Derivative Instruments, Gain (Loss) [Line Items]
Capacity of Electricity (in Megawatts)	151,025
Current | Liquids (gallons)
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	164,682,000	[2]
Noncurrent
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate	2,250
Noncurrent | Natural Gas (bcf): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	68,000,000,000	[1]
Noncurrent | Natural Gas (bcf): | Basis
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	534,000,000,000	[1]
Noncurrent | Electricity (MWh): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	12,582,674	[1]
Noncurrent | Electricity (MWh): | FTRs
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	0
Noncurrent | Capacity (MW)
Derivative Instruments, Gain (Loss) [Line Items]
Capacity of Electricity (in Megawatts)	148,461
Noncurrent | Liquids (gallons)
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	145,698,000	[2]
Virginia Electric and Power Company | Current
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate	500,000,000
Virginia Electric and Power Company | Current | Natural Gas (bcf): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	16,000,000,000
Virginia Electric and Power Company | Current | Natural Gas (bcf): | Basis
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	8,000,000,000
Virginia Electric and Power Company | Current | Electricity (MWh): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	709,600,000,000
Virginia Electric and Power Company | Current | Electricity (MWh): | FTRs
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	43,570,739,000,000
Virginia Electric and Power Company | Current | Capacity (MW)
Derivative Instruments, Gain (Loss) [Line Items]
Capacity of Electricity (in Megawatts)	107,000,000,000
Virginia Electric and Power Company | Noncurrent
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate	$ 250,000,000
Virginia Electric and Power Company | Noncurrent | Natural Gas (bcf): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	0
Virginia Electric and Power Company | Noncurrent | Natural Gas (bcf): | Basis
Derivative Instruments, Gain (Loss) [Line Items]
Volume of natural gas (in billion cubic feet and gallons)	0
Virginia Electric and Power Company | Noncurrent | Electricity (MWh): | Fixed Price
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	0
Virginia Electric and Power Company | Noncurrent | Electricity (MWh): | FTRs
Derivative Instruments, Gain (Loss) [Line Items]
Volume of electricity (in Megawatt hours)	0
Virginia Electric and Power Company | Noncurrent | Capacity (MW)
Derivative Instruments, Gain (Loss) [Line Items]
Capacity of Electricity (in Megawatts)	93,800,000,000

[1] Includes options.

[2] Includes NGLs and oil.