Equity (Narrative) (Details)						1 Months Ended				3 Months Ended	12 Months Ended
	Aug. 15, 2016 shares	[1]	Jul. 01, 2016 shares	Apr. 01, 2016 shares	Jul. 01, 2014 shares	Jan. 31, 2017 USD ($) shares	Jul. 31, 2016 shares	Apr. 30, 2016 USD ($) shares	Dec. 31, 2014 USD ($) agreement	Dec. 31, 2016 USD ($) shares	Dec. 31, 2017 performance_metric	Dec. 31, 2016 USD ($) performance_metric shares	Dec. 31, 2015 USD ($) performance_metric shares	Dec. 31, 2014 USD ($)	Dec. 31, 2007	Jan. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock												$ 2,152,000,000	$ 786,000,000	$ 205,000,000
Common stock, shares outstanding | shares										628,000,000		628,000,000	596,000,000
Net proceeds from issuance of Dominion Midstream common units												$ 482,000,000	$ 0	392,000,000
Net proceeds from issuance of Dominion Midstream convertible preferred units												490,000,000	0	0
Compensation cost related to stock-based compensation												33,000,000	39,000,000	39,000,000
Tax benefit from stock awards and stock options exercised												11,000,000	14,000,000	14,000,000
Tax benefits from the vesting of restricted stock awards (less than $1 million)												$ 1,000,000	$ 3,000,000	1,000,000
Cash-Based Performance Grant | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash-based performance grants minimum percentage															0.00%
Cash-based performance grants maximum percentage															200.00%
February 2014 Awards | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected award under grant																$ 10,000,000
Number of performance metrics achieved | performance_metric													2
February 2015 Cash Based Performance Grant | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance metrics achieved | performance_metric												2
February 2015 Cash Based Performance Grant | Officer | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected award under grant						$ 10,000,000
February 2016 Cash Based Performance Grant | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Targeted amount of the grant										$ 14,000,000		$ 14,000,000
Liability accrued for award										$ 6,000,000		$ 6,000,000
February 2016 Cash Based Performance Grant | Officer | Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance metrics achieved | performance_metric											2
Dominion Direct, Employee Stock Awards, Employee Savings Plans, Director Stock Compensation Plans, and Contingent Convertible Senior Notes
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved and available for issuance | shares										63,000,000		63,000,000
Stock-Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares were available for future grants | shares										24,000,000		24,000,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period												3 years
Unrecognized compensation cost related to nonvested awards										$ 31,000,000		$ 31,000,000
Fair value of restricted stock awards that vested												$ 21,000,000	$ 37,000,000	$ 19,000,000
Goal-Based Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance metrics | performance_metric												2
Performance metrics period												2 years
Shares issued minimum percentage												0.00%
Shares issued maximum percentage												200.00%
Targeted shares expected to be issued | shares										23,000		23,000
Goal-Based Stock | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares converted to one class to another | shares						9,000
Dominion Midstream Limited Partner Common Unit Purchase Program | Limited partner interest in Dominion Midstream | Dominion Midstream Partners, LP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized purchase amount																	$ 50,000,000
Number of common units purchased | shares												658,000	887,000
Value of common units purchased												$ 17,000,000	$ 25,000,000
Maximum | Stock-Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock based awards												8 years
Weighted Average | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected weighted-average period recognized for the unrecognized compensation cost												1 year 10 months 24 days
Capital Unit, Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued | shares	28,000,000				20,000,000
Capital Unit, Class A | Remarketable Subordinated Notes
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock												$ 1,100,000,000
Number of shares issued | shares			8,500,000.0	8,500,000.0			8,500,000.0	8,500,000.0
Various Programs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock												$ 2,200,000,000
Number of shares issued | shares												32,000,000
Common stock, shares outstanding | shares										628,000,000		628,000,000
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash proceeds received from issuance of shares through Dominion Direct and employee savings plans												$ 295,000,000
Number of shares issued through Dominion Direct and employee savings plans | shares												4,000,000
Shelf Registration for Sale of Common Stock through At-the-market Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of sales agency agreements | agreement									4
Shelf Registration for Sale of Common Stock through At-the-market Program | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate amount of common stock in which Dominion may offer under sales agency agreements									$ 500,000,000
Common stock reserved for issuance in connection with stock purchase contracts										$ 200,000,000		$ 200,000,000
Underwritten Public Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock								$ 756,000,000
Number of shares issued in offering | shares								10,200,000
Dominion Midstream Partners, LP | Limited partner interest in Dominion Midstream
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net proceeds from issuance of Dominion Midstream common units										$ 482,000,000
Conversion basis										1		1
Dominion Midstream Partners, LP | Limited partner interest in Dominion Midstream | Convertible Preferred Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net proceeds from issuance of Dominion Midstream convertible preferred units										$ 490,000,000

[1] The maturity dates of the $700 million Series A-1 RSNs and $700 million Series A-2 RSNs are August 15, 2021 and August 15, 2024, respectively.