Investments (Marketable Equity and Debt Securities and Cash Equivalents (Classified as Available-for-sale) and Cost Method Investments in Decommissioning Trust Funds) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Amortized Cost, Total		$ 3,034	$ 2,936
Total Unrealized Gains	[1]	1,394	1,258
Total Unrealized Losses	[1],[2]	(1)	(11)
Fair Value		4,427	4,183	[3]
Net assets related to pending sales and purchases of securities		9	12
Fair value of securities in an unrealized loss position		156	592
Cost method investments
Investment Holdings [Line Items]
Amortized Cost, Other Investments		69	70
Total Unrealized Gains	[1]	0	0
Total Unrealized Losses	[1]	0	0
Fair Value		69	70
Cash equivalents and other
Investment Holdings [Line Items]
Amortized Cost, Other Investments	[4]	12	14
Total Unrealized Gains	[1],[4]	0	0
Total Unrealized Losses	[1],[4]	0	0
Fair Value	[4]	12	14
Equity securities | Large cap | United States:
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		1,361	1,295
Total Unrealized Gains	[1]	1,312	1,213
Total Unrealized Losses	[1]	0	0
Fair Value		2,673	2,508
Equity securities | REIT
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		59	59
Total Unrealized Gains	[1]	8	4
Total Unrealized Losses	[1]	0	0
Fair Value		67	63
Corporate bonds
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		493	433
Total Unrealized Gains	[1]	26	11
Total Unrealized Losses	[1]	(1)	(7)
Fair Value		518	437
United States Treasury securities and agency debentures
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		645	654
Total Unrealized Gains	[1]	21	8
Total Unrealized Losses	[1]	0	(4)
Fair Value		666	658
State and municipal
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		306	312
Total Unrealized Gains	[1]	27	22
Total Unrealized Losses	[1]	0	0
Fair Value		333	334
Other
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		89	99
Total Unrealized Gains	[1]	0	0
Total Unrealized Losses	[1]	0	0
Fair Value		89	99
Virginia Electric and Power Company
Investment Holdings [Line Items]
Amortized Cost, Total		1,457	1,404
Total Unrealized Gains	[5]	617	548
Total Unrealized Losses	[5],[6]	0	(7)
Fair Value		2,074	1,945	[7]
Net assets related to pending sales and purchases of securities		4	8
Fair value of securities in an unrealized loss position		91	281
Virginia Electric and Power Company | Cost method investments
Investment Holdings [Line Items]
Amortized Cost, Other Investments		69	70
Total Unrealized Gains	[5]	0	0
Total Unrealized Losses	[5]	0	0
Fair Value		69	70
Virginia Electric and Power Company | Cash equivalents and other
Investment Holdings [Line Items]
Amortized Cost, Other Investments	[8]	5	8
Total Unrealized Gains	[5],[8]	0	0
Total Unrealized Losses	[5],[8]	0	0
Fair Value	[8]	5	8
Virginia Electric and Power Company | Equity securities | Large cap | United States:
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		606	574
Total Unrealized Gains	[5]	576	525
Total Unrealized Losses	[5]	0	0
Fair Value		1,182	1,099
Virginia Electric and Power Company | Equity securities | REIT
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		59	59
Total Unrealized Gains	[5]	8	4
Total Unrealized Losses	[5]	0	0
Fair Value		67	63
Virginia Electric and Power Company | Corporate bonds
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		285	237
Total Unrealized Gains	[5]	13	5
Total Unrealized Losses	[5]	0	(4)
Fair Value		298	238
Virginia Electric and Power Company | United States Treasury securities and agency debentures
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		246	260
Total Unrealized Gains	[5]	5	1
Total Unrealized Losses	[5]	0	(2)
Fair Value		251	259
Virginia Electric and Power Company | State and municipal
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		158	162
Total Unrealized Gains	[5]	15	13
Total Unrealized Losses	[5]	0	(1)
Fair Value		173	174
Virginia Electric and Power Company | Other
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		29	34
Total Unrealized Gains	[5]	0	0
Total Unrealized Losses	[5]	0	0
Fair Value		$ 29	$ 34

[1] Included in AOCI and the nuclear decommissioning trust regulatory liability.

[2] The fair value of securities in an unrealized loss position was $156 million and $592 million at September 30, 2016 and December 31, 2015, respectively.

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

[4] Includes pending sales of securities of $9 million and $12 million at September 30, 2016 and December 31, 2015, respectively.

[5] Included in AOCI and the nuclear decommissioning trust regulatory liability.

[6] The fair value of securities in an unrealized loss position was $91 million and $281 million at September 30, 2016 and December 31, 2015, respectively.

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

[8] Includes pending sales of securities of $4 million and $8 million at September 30, 2016 and December 31, 2015, respectively.