Accumulated Other Comprehensive Income (Schedule of Reclassifications out of AOCI by Component Net of Tax) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating revenue		$ (2,598)	$ (2,747)	$ (5,519)	$ (6,156)
Purchased gas		56	111	175	361
Electric fuel and other energy-related purchases		551	591	1,185	1,544
Interest and related charges		239	221	465	444
Other income		(72)	(56)	(126)	(116)
Income from operations including noncontrolling interests before income tax expense		(614)	(608)	(1,324)	(1,447)
Income tax expense		152	190	331	489
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating revenue	[1]	(368)	(395)	(799)	(926)
Purchased gas	[1]	16	21	50	95
Interest and related charges		23	18	45	35
Other income		(9)	(4)	(15)	(13)
Income from operations including noncontrolling interests before income tax expense		(172)	(139)	(331)	(402)
Income tax expense		67	54	128	156
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	(44)	(61)	(107)	(2)
Deferred Gains and Losses on Derivatives-Hedging Activities | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	0	(1)	(2)	(1)
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		(72)	(102)	(174)	(4)
Income tax expense		28	41	67	2
Income from continuing operations including noncontrolling interests		(44)	(61)	(107)	(2)
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		2	(1)	(2)	(1)
Income tax expense		(2)	0	0	0
Income from continuing operations including noncontrolling interests		0	(1)	(2)	(1)
Deferred Gains and Losses on Derivatives-Hedging Activities | Commodity contracts | Amounts Reclassified From AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating revenue		(87)	(107)	(201)	(15)
Purchased gas		2	2	8	7
Electric fuel and other energy-related purchases		3		6	1
Deferred Gains and Losses on Derivatives-Hedging Activities | Commodity contracts | Amounts Reclassified From AOCI | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating revenue			(1)	(4)	(1)
Deferred Gains and Losses on Derivatives-Hedging Activities | Foreign currency contracts | Amounts Reclassified From AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and related charges		8	3	11	5
Deferred Gains and Losses on Derivatives-Hedging Activities | Foreign currency | Amounts Reclassified From AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income		2		2
Deferred Gains and Losses on Derivatives-Hedging Activities | Foreign currency | Amounts Reclassified From AOCI | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income		2		2
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	(8)	(12)	(10)	(33)
Unrealized Gains and Losses on Investment Securities | Amounts Reclassified From AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Realized (gain) loss on sale of securities		(20)	(25)	(30)	(64)
Impairment		7	5	14	11
Income from operations including noncontrolling interests before income tax expense		(13)	(20)	(16)	(53)
Income tax expense		5	8	6	20
Income from continuing operations including noncontrolling interests		(8)	(12)	(10)	(33)
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		14	21	28	43
Unrecognized pension and other postretirement benefit costs, income tax expense		(6)	(9)	(12)	(18)
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	8	12	16	25
Unrecognized Pension and Other Postretirement Benefit Costs | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		1	2	2	4
Unrecognized pension and other postretirement benefit costs, income tax expense		0	(1)	(1)	(2)
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	1	1	1	2
Prior service (credit) costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		(3)	(3)	(7)	(6)
Actuarial (gains) losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		17	24	35	49
Actuarial (gains) losses | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		$ 1	$ 2	$ 2	$ 4

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

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