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)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Loss Carryforwards [Line Items]
U.S. statutory rate	35.00%	35.00%
Increases (reductions) resulting from:
State taxes, net of federal benefit	4.00%	2.70%
Investment tax credits	(3.50%)	(6.00%)
Production tax credits	(0.80%)	(1.10%)
Other, net	(0.90%)	0.10%
Effective tax rate	33.80%	30.70%
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%	3.90%
Investment tax credits	(0.00%)	(0.00%)
Production tax credits	(0.50%)	(0.60%)
Other, net	(0.20%)	0.80%
Effective tax rate	38.50%	39.10%
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	4.10%	3.70%
Investment tax credits	(0.00%)	(0.00%)
Production tax credits	(0.00%)	(0.00%)
Other, net	0.40%	0.10%
Effective tax rate	39.50%	38.80%