Accumulated Other Comprehensive Income (Schedule of Changes in 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), Net of Tax [Roll Forward]
Beginning balance	[1]			$ 13,602
Total other comprehensive income (loss)		$ (30)	$ 23	(19)	$ 30
Ending balance		15,452		15,452
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total other comprehensive income (loss)		(8)	3	(16)	0
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(463)	(409)	(474)	(416)
Other comprehensive income before reclassifications: gains (losses)		14	84	82	40
Amounts reclassified from AOCI: (gains) losses	[2]	(44)	(61)	(101)	(10)
Total other comprehensive income (loss)		(30)	23	(19)	30
Ending balance		(493)	(386)	(493)	(386)
Total | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(107)	(89)	(99)	(86)
Other comprehensive income before reclassifications: gains (losses)		(9)	3	(15)	(1)
Amounts reclassified from AOCI: (gains) losses	[2]	1	0	(1)	1
Total other comprehensive income (loss)		(8)	3	(16)	0
Ending balance		(115)	(86)	(115)	(86)
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(186)	(177)	(176)	(178)
Other comprehensive income before reclassifications: gains (losses)		(11)	92	42	34
Amounts reclassified from AOCI: (gains) losses	[2]	(44)	(61)	(107)	(2)
Total other comprehensive income (loss)		(55)	31	(65)	32
Ending balance		(241)	(146)	(241)	(146)
Deferred Gains and Losses on Derivatives-Hedging Activities | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(25)	(24)	(17)	(20)
Other comprehensive income before reclassifications: gains (losses)		(9)	3	(15)	(1)
Amounts reclassified from AOCI: (gains) losses	[2]	0	(1)	(2)	(1)
Total other comprehensive income (loss)		(9)	2	(17)	(2)
Ending balance		(34)	(22)	(34)	(22)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		517	542	504	548
Other comprehensive income before reclassifications: gains (losses)		26	(11)	41	4
Amounts reclassified from AOCI: (gains) losses	[2]	(8)	(12)	(10)	(33)
Total other comprehensive income (loss)		18	(23)	31	(29)
Ending balance		535	519	535	519
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(789)	(769)	(797)	(782)
Other comprehensive income before reclassifications: gains (losses)		0	3	0	3
Amounts reclassified from AOCI: (gains) losses	[2]	8	12	16	25
Total other comprehensive income (loss)		8	15	16	28
Ending balance		(781)	(754)	(781)	(754)
Unrecognized Pension and Other Postretirement Benefit Costs | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(82)	(65)	(82)	(66)
Other comprehensive income before reclassifications: gains (losses)		0	0	0	0
Amounts reclassified from AOCI: (gains) losses	[2]	1	1	1	2
Total other comprehensive income (loss)		1	1	1	2
Ending balance		(81)	(64)	(81)	(64)
Other Comprehensive Income (Loss) From Equity Method Investee
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(5)	(5)	(5)	(4)
Other comprehensive income before reclassifications: gains (losses)		(1)	0	(1)	(1)
Amounts reclassified from AOCI: (gains) losses	[2]	0	0	0	0
Total other comprehensive income (loss)		(1)	0	(1)	(1)
Ending balance		$ (6)	$ (5)	$ (6)	$ (5)

[1] Dominion’s Consolidated Balance Sheet at December 31, 2015 has been derived from the audited Consolidated Financial Statements at that date.

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