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		Mar. 31, 2017	Dec. 31, 2016
Investment Holdings [Line Items]
Amortized Cost, Total		$ 3,149	$ 3,053
Total Unrealized Gains	[1]	1,515	1,443
Total Unrealized Losses	[1],[2]	(9)	(12)
Fair Value		4,655	4,484	[3]
Net assets related to pending sales and purchases of securities		2	9
Fair value of securities in an unrealized loss position		461	576
Cost method investments
Investment Holdings [Line Items]
Amortized Cost, Other Investments		69	69
Total Unrealized Gains	[1]	0	0
Total Unrealized Losses	[1]	0	0
Fair Value		69	69
Cash equivalents and other
Investment Holdings [Line Items]
Amortized Cost, Other Investments	[4]	6	12
Total Unrealized Gains	[1],[4]	0	0
Total Unrealized Losses	[1],[4]	0	0
Fair Value	[4]	6	12
Corporate debt instruments
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		488	478
Total Unrealized Gains	[1]	13	13
Total Unrealized Losses	[1]	(3)	(4)
Fair Value		498	487
Government securities
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		977	978
Total Unrealized Gains	[1]	24	22
Total Unrealized Losses	[1]	(6)	(8)
Fair Value		995	992
Common/collective trust funds
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		66	67
Total Unrealized Gains	[1]	0	0
Total Unrealized Losses	[1]	0	0
Fair Value		66	67
Virginia Electric and Power Company
Investment Holdings [Line Items]
Amortized Cost, Total		1,519	1,473
Total Unrealized Gains	[5]	671	639
Total Unrealized Losses	[5],[6]	(4)	(6)
Fair Value		2,186	2,106	[7]
Net assets related to pending sales and purchases of securities		4	7
Fair value of securities in an unrealized loss position		214	287
Virginia Electric and Power Company | Cost method investments
Investment Holdings [Line Items]
Amortized Cost, Other Investments		69	69
Total Unrealized Gains	[5]	0	0
Total Unrealized Losses	[5]	0	0
Fair Value		69	69
Virginia Electric and Power Company | Cash equivalents and other
Investment Holdings [Line Items]
Amortized Cost, Other Investments	[8]	4	7
Total Unrealized Gains	[5],[8]	0	0
Total Unrealized Losses	[5],[8]	0	0
Fair Value	[8]	4	7
Virginia Electric and Power Company | Corporate debt instruments
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		278	274
Total Unrealized Gains	[5]	6	6
Total Unrealized Losses	[5]	(2)	(4)
Fair Value		282	276
Virginia Electric and Power Company | Government securities
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		418	420
Total Unrealized Gains	[5]	11	9
Total Unrealized Losses	[5]	(2)	(2)
Fair Value		427	427
Virginia Electric and Power Company | Common/collective trust funds
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		30	26
Total Unrealized Gains	[5]	0	0
Total Unrealized Losses	[5]	0	0
Fair Value		30	26
U.S. | Equity securities
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		1,543	1,449
Total Unrealized Gains	[1]	1,478	1,408
Total Unrealized Losses	[1]	0	0
Fair Value		3,021	2,857
U.S. | Virginia Electric and Power Company | Equity securities
Investment Holdings [Line Items]
Amortized Cost, Marketable Securities		720	677
Total Unrealized Gains	[5]	654	624
Total Unrealized Losses	[5]	0	0
Fair Value		$ 1,374	$ 1,301

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

[2] The fair value of securities in an unrealized loss position was $461 million and $576 million at March 31, 2017 and December 31, 2016, respectively.

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

[4] Includes net pending sales of securities of $2 million and $9 million at March 31, 2017 and December 31, 2016, respectively.

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

[6] The fair value of securities in an unrealized loss position was $214 million and $287 million at March 31, 2017 and December 31, 2016, respectively.

[7] Virginia Power’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.

[8] Includes pending sales of securities of $4 million and $7 million at March 31, 2017 and December 31, 2016, respectively.