Fair Value Measurements (Net Change in the Assets and Liabilities Measured at Fair Value on a Recurring Basis and Included in the Level 3 Fair Value Category) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Total realized and unrealized gains (losses):
Included in earnings	$ 15		$ 110
The amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets/liabilities still held at the reporting date	0		1
Level 3 | Commodity Transactions | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	107		(16)
Total realized and unrealized gains (losses):
Included in earnings	15		110
Included in other comprehensive income (loss)	(11)		4
Included in regulatory assets/liabilities	(24)		17
Settlements	(14)		(108)
Transfers out of Level 3(1)	3	[1]	1	[1]
Ending balance	76		8
The amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets/liabilities still held at the reporting date	0		1
Level 3 | NGLs | Fair Value, Measurements, Recurring
Total realized and unrealized gains (losses):
Transfers out of Level 3(1)	9	[1]
Level 3 | Virginia Electric and Power Company | Commodity Transactions | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	102		(7)
Total realized and unrealized gains (losses):
Included in earnings	14		120
Included in regulatory assets/liabilities	(24)		17
Settlements	(14)		(120)
Ending balance	78		10
Level 3 | Dominion Gas Holdings, LLC | Commodity Transactions | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	2		(6)
Total realized and unrealized gains (losses):
Included in earnings	1		(5)
Included in other comprehensive income (loss)	(11)		4
Settlements	(1)		5
Transfers out of Level 3(1)	9	[1]	0	[1]
Ending balance	0		(2)
Level 3 | Dominion Gas Holdings, LLC | NGLs | Fair Value, Measurements, Recurring
Total realized and unrealized gains (losses):
Transfers out of Level 3(1)	$ 9	[1]

[1] In March 2015, Dominion changed the classification of NGL derivatives from Level 3 to Level 2 due to an increase in liquidity in financial forward markets. At March 31, 2015, $9 million of the transfers out of Level 3 relate to NGLs.