Accumulated Other Comprehensive Income (Schedule of Reclassifications out of AOCI by Component Net of Tax) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue		$ 2,921	$ 3,409
Purchased gas		119	250
Electric fuel and other energy-related purchases		634	953
Interest and related charges		226	223
Income from operations including noncontrolling interests before income tax expense		710	839
Income tax expense		(179)	(299)
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue	[1]	431	531
Purchased gas	[1]	34	74
Interest and related charges		22	17
Income from operations including noncontrolling interests before income tax expense		159	263
Income tax expense		(61)	(102)
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]	(63)	59
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]	(2)	0
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		(102)	98
Income tax expense		39	(39)
Income from continuing operations including noncontrolling interests		(63)	59
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		(4)
Income tax expense		2
Income from continuing operations including noncontrolling interests		(2)
Deferred Gains and Losses on Derivatives-Hedging Activities | Commodity contracts | Amounts Reclassified From AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenue		(114)	92
Purchased gas		6	5
Electric fuel and other energy-related purchases		3	(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		(4)
Deferred Gains and Losses on Derivatives-Hedging Activities | Interest rate contracts | Amounts Reclassified From AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and related charges		3	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]	(2)	(21)
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		(10)	(39)
Impairment		7	6
Income from operations including noncontrolling interests before income tax expense		3	33
Income tax expense		(1)	(12)
Income from continuing operations including noncontrolling interests		2	21
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		14	22
Unrecognized pension and other postretirement benefit costs, income tax expense		(6)	(9)
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	8	13
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
Unrecognized pension and other postretirement benefit costs, income tax expense		(1)	(1)
Unrecognized pension and other postretirement benefit costs, net of tax	[2]	0	1
Prior service (credit) costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		(3)	(3)
Actuarial (gains) losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrecognized pension and other postretirement benefit costs, before tax		17	25
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

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

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