Accumulated Other Comprehensive Income (Schedule of Reclassifications out of AOCI by Component Net of Tax) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue		$ 2,971	$ 3,050	$ 9,127	$ 9,493
Purchased gas		85	209	446	1,073
Electric fuel and other energy-related purchases		636	743	2,180	2,710
Interest and related charges		230	231	674	695
Other income		11	69	127	166
Impairment		16	4	27	13
Income from operations including noncontrolling interests before income tax expense		904	759	2,351	1,554
Income tax expense		(305)	(228)	(794)	(477)
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue	[1]	365	391	1,291	1,388
Purchased gas	[1]	8	34	103	247
Interest and related charges		18	7	53	19
Other income		4	5	17	18
Income from operations including noncontrolling interests before income tax expense		188	175	590	595
Income tax expense		(77)	(68)	(233)	(231)
Deferred gains and losses on derivatives-hedging activities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income from operations including noncontrolling interests before income tax expense		(83)	(53)	(87)	185
Income tax expense		30	22	34	(72)
Income from continuing operations including noncontrolling interests		(53)	(31)	(53)	113
Deferred gains and losses on derivatives-hedging activities | Amounts reclassified from AOCI | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income from operations including noncontrolling interests before income tax expense		(3)	6	(4)	18
Income tax expense		1	(2)	1	(7)
Income from continuing operations including noncontrolling interests		(2)	4	(3)	11
Unrealized gains and losses on investment securities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income		(18)	(38)	(82)	(71)
Impairment		16	4	27	8
Income from operations including noncontrolling interests before income tax expense		(2)	(34)	(55)	(63)
Income tax expense		0	13	20	24
Income from continuing operations including noncontrolling interests		(2)	(21)	(35)	(39)
Unrecognized pension and other postretirement benefit costs | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service (credit) costs		(3)	(4)	(9)	(9)
Actuarial (gains) losses		24	18	73	52
Income from operations including noncontrolling interests before income tax expense		21	14	64	43
Income tax expense		(7)	(6)	(25)	(18)
Income from continuing operations including noncontrolling interests		14	8	39	25
Unrecognized pension and other postretirement benefit costs | Amounts reclassified from AOCI | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Actuarial (gains) losses		2	2	6	5
Income from operations including noncontrolling interests before income tax expense		2	2	6	5
Income tax expense		(1)	(1)	(3)	(2)
Income from continuing operations including noncontrolling interests		1	1	3	3
Commodity contracts | Deferred gains and losses on derivatives-hedging activities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue		(87)	(66)	(103)	175
Purchased gas		2	3	9	7
Electric fuel and other energy-related purchases			5		(8)
Commodity contracts | Deferred gains and losses on derivatives-hedging activities | Amounts reclassified from AOCI | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue		(3)	1	(4)	8
Purchased gas			5		10
Interest rate contracts | Deferred gains and losses on derivatives-hedging activities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and related charges		$ 2	$ 5	$ 7	$ 11

[1] See Note 18 for amounts attributable to related parties.