Earnings Per Share (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to Dominion		$ 690	$ 593	$ 1,666	$ 1,542
Average shares of common stock outstanding – Basic (shares)		625.9	594.6	612.8	591.3
Net effect of dilutive securities (shares)	[1]	0.1	0.9	1.0	1.4
Average shares of common stock outstanding – Diluted (shares)		626.0	595.5	613.8	592.7
Earnings Per Common Share – Basic (in dollars per share)		$ 1.10	$ 1.00	$ 2.72	$ 2.61
Earnings Per Common Share – Diluted (in dollars per share)		$ 1.10	$ 1.00	$ 2.71	$ 2.60

[1] Dilutive securities consist primarily of the 2013 Equity Units for the nine months ended September 30, 2016 and the three and nine months ended September 30, 2015. See Note 14 in this report and Note 17 to the Consolidated Financial Statements in the Companies' Annual Report on Form 10-K for the year ended December 31, 2015 for more information.