Accumulated Other Comprehensive Income (Schedule of Changes in AOCI by Component Net of Tax) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (416)	[1]	$ (324)
Other comprehensive income before reclassifications: gains (losses)	(44)		(132)
Amounts reclassified from AOCI: (gains) losses	51	[2]	157	[2]
Total other comprehensive income	7		25
Ending balance	(409)		(299)
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(86)	[3],[4]	(58)
Other comprehensive income before reclassifications: gains (losses)	(4)		(8)
Amounts reclassified from AOCI: (gains) losses	1	[2]	6	[2]
Total other comprehensive income	(3)		(2)
Ending balance	(89)	[3]	(60)
Deferred gains and losses on derivatives-hedging activities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(178)		(288)
Other comprehensive income before reclassifications: gains (losses)	(58)		(150)
Amounts reclassified from AOCI: (gains) losses	59	[2]	160	[2]
Total other comprehensive income	1		10
Ending balance	(177)		(278)
Deferred gains and losses on derivatives-hedging activities | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(20)		3
Other comprehensive income before reclassifications: gains (losses)	(4)		(8)
Amounts reclassified from AOCI: (gains) losses	0	[2]	5	[2]
Total other comprehensive income	(4)		(3)
Ending balance	(24)		0
Unrealized gains and losses on investment securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	548		474
Other comprehensive income before reclassifications: gains (losses)	15		29
Amounts reclassified from AOCI: (gains) losses	(21)	[2]	(11)	[2]
Total other comprehensive income	(6)		18
Ending balance	542		492
Unrecognized pension and other postretirement benefit costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(782)		(510)
Other comprehensive income before reclassifications: gains (losses)	0		(4)
Amounts reclassified from AOCI: (gains) losses	13	[2]	8	[2]
Total other comprehensive income	13		4
Ending balance	(769)		(506)
Unrecognized pension and other postretirement benefit costs | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(66)		(61)
Other comprehensive income before reclassifications: gains (losses)	0		0
Amounts reclassified from AOCI: (gains) losses	1	[2]	1	[2]
Total other comprehensive income	1		1
Ending balance	(65)		(60)
Other comprehensive income (loss) from equity method investee
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(4)		0
Other comprehensive income before reclassifications: gains (losses)	(1)		(7)
Amounts reclassified from AOCI: (gains) losses	0	[2]	0	[2]
Total other comprehensive income	(1)		(7)
Ending balance	$ (5)		$ (7)

[1] Dominion’s Consolidated Balance Sheet at December 31, 2014 has been derived from the audited Consolidated Financial Statements at that date.

[2] See table below for details about these reclassifications.

[3] See Note 17 for amounts attributable to related parties.

[4] Dominion Gas’ Consolidated Balance Sheet at December 31, 2014 has been derived from the audited Consolidated Financial Statements at that date.