Accumulated Other Comprehensive Income (Schedule of Changes in AOCI by Component Net of Tax) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	[1]	$ 13,602
Total other comprehensive income		11	$ 7
Ending balance		14,015
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total other comprehensive income		(8)	(3)
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(474)	(416)
Other comprehensive income before reclassifications: gains (losses)		68	(44)
Amounts reclassified from AOCI: (gains) losses	[2]	(57)	51
Total other comprehensive income		11	7
Ending balance		(463)	(409)
Total | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(99)	(86)
Other comprehensive income before reclassifications: gains (losses)		(6)	(4)
Amounts reclassified from AOCI: (gains) losses	[2]	(2)	1
Total other comprehensive income		(8)	(3)
Ending balance		(107)	(89)
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(176)	(178)
Other comprehensive income before reclassifications: gains (losses)		53	(58)
Amounts reclassified from AOCI: (gains) losses	[2]	(63)	59
Total other comprehensive income		(10)	1
Ending balance		(186)	(177)
Deferred Gains and Losses on Derivatives-Hedging Activities | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(17)	(20)
Other comprehensive income before reclassifications: gains (losses)		(6)	(4)
Amounts reclassified from AOCI: (gains) losses	[2]	(2)	0
Total other comprehensive income		(8)	(4)
Ending balance		(25)	(24)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		504	548
Other comprehensive income before reclassifications: gains (losses)		15	15
Amounts reclassified from AOCI: (gains) losses	[2]	(2)	(21)
Total other comprehensive income		13	(6)
Ending balance		517	542
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(797)	(782)
Other comprehensive income before reclassifications: gains (losses)		0	0
Amounts reclassified from AOCI: (gains) losses	[2]	8	13
Total other comprehensive income		8	13
Ending balance		(789)	(769)
Unrecognized Pension and Other Postretirement Benefit Costs | Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(82)	(66)
Other comprehensive income before reclassifications: gains (losses)		0	0
Amounts reclassified from AOCI: (gains) losses	[2]	0	1
Total other comprehensive income		0	1
Ending balance		(82)	(65)
Other Comprehensive Income (Loss) From Equity Method Investee
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(5)	(4)
Other comprehensive income before reclassifications: gains (losses)		0	(1)
Amounts reclassified from AOCI: (gains) losses	[2]	0	0
Total other comprehensive income		0	(1)
Ending balance		$ (5)	$ (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.