Fair Value Measurements (Fair Value, Option, Quantitative Disclosures) (Details) $ in Millions		6 Months Ended
		Jun. 30, 2016 USD ($) $ / MWh $ / MMBTU	Dec. 31, 2015 USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 354	$ 388
Fair Value of Derivative Liabilities		473	343
Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		137
Fair Value of Derivative Liabilities		13
Level 3 | Natural Gas | Physical and financial forwards and futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets	[1]	123
Fair Value of Derivative Liabilities	[1]	5
Level 3 | Natural Gas | Physical and financial options:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		8
Fair Value of Derivative Liabilities		1
Level 3 | FTRs | Physical and financial forwards and futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		6
Fair Value of Derivative Liabilities		$ 7
Level 3 | Liabilities | Natural Gas | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	(1)
Level 3 | Liabilities | Natural Gas | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	4
Level 3 | Liabilities | Natural Gas | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2],[3]	3
Level 3 | Liabilities | Natural Gas | Physical and financial options: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	2
Price Volatility (percentage)	[4]	29.00%
Level 3 | Liabilities | Natural Gas | Physical and financial options: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	4
Price Volatility (percentage)	[4]	42.00%
Level 3 | Liabilities | Natural Gas | Physical and financial options: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2],[3]	3
Price Volatility (percentage)	[3],[4]	36.00%
Level 3 | Liabilities | FTRs | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[2]	(2)
Level 3 | Liabilities | FTRs | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[2]	5
Level 3 | Liabilities | FTRs | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[2],[3]	1
Level 3 | Assets | Natural Gas | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	(2)
Credit spread (percentage)	[5]	1.00%
Level 3 | Assets | Natural Gas | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	7
Credit spread (percentage)	[5]	6.00%
Level 3 | Assets | Natural Gas | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2],[3]	0
Credit spread (percentage)	[3],[5]	3.00%
Level 3 | Assets | Natural Gas | Physical and financial options: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	2
Price Volatility (percentage)	[4]	20.00%
Level 3 | Assets | Natural Gas | Physical and financial options: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2]	7
Price Volatility (percentage)	[4]	42.00%
Level 3 | Assets | Natural Gas | Physical and financial options: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[2],[3]	4
Price Volatility (percentage)	[3],[4]	25.00%
Level 3 | Assets | FTRs | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[2]	(8)
Level 3 | Assets | FTRs | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[2]	3
Level 3 | Assets | FTRs | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[2],[3]	1
Virginia Electric and Power Company
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 163	127
Fair Value of Derivative Liabilities		274	86
Virginia Electric and Power Company | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		132
Fair Value of Derivative Liabilities		7
Virginia Electric and Power Company | Level 3 | Natural Gas | Physical and financial forwards and futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets	[6]	121
Virginia Electric and Power Company | Level 3 | Natural Gas | Physical and financial options:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		5
Virginia Electric and Power Company | Level 3 | FTRs | Physical and financial forwards and futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		6
Fair Value of Derivative Liabilities		$ 7
Virginia Electric and Power Company | Level 3 | Liabilities | Natural Gas | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[7]	(2)
Virginia Electric and Power Company | Level 3 | Liabilities | Natural Gas | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[7]	5
Virginia Electric and Power Company | Level 3 | Liabilities | FTRs | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[7],[8]	1
Virginia Electric and Power Company | Level 3 | Assets | Natural Gas | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[7]	(2)
Credit spread (percentage)	[9]	1.00%
Virginia Electric and Power Company | Level 3 | Assets | Natural Gas | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[7]	7
Credit spread (percentage)	[9]	6.00%
Virginia Electric and Power Company | Level 3 | Assets | Natural Gas | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[7],[8]	0
Credit spread (percentage)	[8],[9]	3.00%
Virginia Electric and Power Company | Level 3 | Assets | Natural Gas | Physical and financial options: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[7]	2
Price Volatility (percentage)	[10]	20.00%
Virginia Electric and Power Company | Level 3 | Assets | Natural Gas | Physical and financial options: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[7]	7
Price Volatility (percentage)	[10]	33.00%
Virginia Electric and Power Company | Level 3 | Assets | Natural Gas | Physical and financial options: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[7],[8]	4
Price Volatility (percentage)	[8],[10]	24.00%
Virginia Electric and Power Company | Level 3 | Assets | FTRs | Physical and financial forwards and futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[7]	(8)
Virginia Electric and Power Company | Level 3 | Assets | FTRs | Physical and financial forwards and futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[7]	3
Virginia Electric and Power Company | Level 3 | Assets | FTRs | Physical and financial forwards and futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[7],[8]	1
Dominion Gas Holdings, LLC
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 3	11
Fair Value of Derivative Liabilities		$ 12	$ 14

[1] Includes basis.

[2] Represents market prices beyond defined terms for Levels 1 and 2.

[3] Averages weighted by volume.

[4] Represents volatilities unrepresented in published markets.

[5] Represents credit spreads unrepresented in published markets.

[6] Includes basis.

[7] Represents market prices beyond defined terms for Levels 1 and 2.

[8] Averages weighted by volume.

[9] Represents credit spreads unrepresented in published markets.

[10] Represents volatilities unrepresented in published markets.