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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]			$ 14,605
Total other comprehensive income (loss)				117	$ (19)
Ending balance		$ 14,973		14,973
Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[2]			3,536
Total other comprehensive income (loss)		1	$ (8)	3	(16)
Ending balance		3,711		3,711
Deferred Gains and Losses on Derivatives-Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(260)	(186)	(280)	(176)
Other comprehensive income before reclassifications: gains (losses)		28	(11)	71	42
Amounts reclassified from AOCI: (gains) losses	[3]	(18)	(44)	(41)	(107)
Total other comprehensive income (loss)		10	(55)	30	(65)
Ending balance		(250)	(241)	(250)	(241)
Deferred Gains and Losses on Derivatives-Hedging Activities | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(22)	(25)	(24)	(17)
Other comprehensive income before reclassifications: gains (losses)		11	(9)	2	(15)
Amounts reclassified from AOCI: (gains) losses	[3]	(12)	0	(1)	(2)
Total other comprehensive income (loss)		(1)	(9)	1	(17)
Ending balance		(23)	(34)	(23)	(34)
Unrealized Gains and Losses on Investment Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		599	517	569	504
Other comprehensive income before reclassifications: gains (losses)		35	26	93	41
Amounts reclassified from AOCI: (gains) losses	[3]	(4)	(8)	(32)	(10)
Total other comprehensive income (loss)		31	18	61	31
Ending balance		630	535	630	535
Unrecognized Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,069)	(789)	(1,082)	(797)
Other comprehensive income before reclassifications: gains (losses)		0	0	0	0
Amounts reclassified from AOCI: (gains) losses	[3]	11	8	24	16
Total other comprehensive income (loss)		11	8	24	16
Ending balance		(1,058)	(781)	(1,058)	(781)
Unrecognized Pension and Other Postretirement Benefit Costs | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(99)	(82)	(99)	(82)
Other comprehensive income before reclassifications: gains (losses)		0	0	0	0
Amounts reclassified from AOCI: (gains) losses	[3]	2	1	2	1
Total other comprehensive income (loss)		2	1	2	1
Ending balance		(97)	(81)	(97)	(81)
Other Comprehensive Income (Loss) From Equity Method Investee
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(5)	(5)	(6)	(5)
Other comprehensive income before reclassifications: gains (losses)		1	(1)	2	(1)
Amounts reclassified from AOCI: (gains) losses	[3]	0	0	0	0
Total other comprehensive income (loss)		1	(1)	2	(1)
Ending balance		(4)	(6)	(4)	(6)
Total
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(735)	(463)	(799)	(474)
Other comprehensive income before reclassifications: gains (losses)		64	14	166	82
Amounts reclassified from AOCI: (gains) losses	[3]	(11)	(44)	(49)	(101)
Total other comprehensive income (loss)		53	(30)	117	(19)
Ending balance		(682)	(493)	(682)	(493)
Total | Dominion Energy Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(121)	(107)	(123)	(99)
Other comprehensive income before reclassifications: gains (losses)		11	(9)	2	(15)
Amounts reclassified from AOCI: (gains) losses	[3]	(10)	1	1	(1)
Total other comprehensive income (loss)		1	(8)	3	(16)
Ending balance		$ (120)	$ (115)	$ (120)	$ (115)

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Dominion Energy Gas’ Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.

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