Income Taxes (Reconciliation of Income Taxes at the U.S. Statutory Federal Rate as Compared to the Income Tax Expense Recorded in Our Consolidated Statements of Income) (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%	35.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.30%	2.90%
Investment tax credits	(10.90%)	(0.80%)
Production tax credits	(0.80%)	(0.80%)
Other, net	(2.40%)	(0.60%)
Effective tax rate	25.20%	35.70%
Virginia Electric and Power Company
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%	35.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.20%	3.80%
Investment tax credits	(1.30%)	(0.00%)
Production tax credits	(0.60%)	(0.40%)
Other, net	(0.60%)	(0.70%)
Effective tax rate	36.70%	37.70%
Dominion Gas Holdings, LLC
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%	35.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	3.90%	4.00%
Investment tax credits	(0.00%)	(0.00%)
Production tax credits	(0.00%)	(0.00%)
Other, net	(0.10%)	(0.10%)
Effective tax rate	38.80%	38.90%