Employee Benefit Plans (Narrative) (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined benefit pension plans and OPEB plans		$ 0
Expected contribution to voluntary employees' beneficiary association		12,000,000
Medical Coverage for Local 50 retirees
Defined Benefit Plan Disclosure [Line Items]
Retirement age	65 years
Decrease in accumulated postretirement benefit obligation	$ 37,000,000	37,000,000
Increase in net periodic benefit credit	$ 9,000,000	$ 9,000,000
Discount rate percentage	3.71%	3.71%
Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined benefit pension plans and OPEB plans		$ 0
Expected contribution to voluntary employees' beneficiary association		12,000,000
Special Termination Benefits | Organizational Design Initiative
Defined Benefit Plan Disclosure [Line Items]
Organizational design initiative		65,000,000
Organizational design initiative, after tax		40,000,000
Special Termination Benefits | Organizational Design Initiative | Virginia Electric and Power Company
Defined Benefit Plan Disclosure [Line Items]
Organizational design initiative		33,000,000
Organizational design initiative, after tax		20,000,000
Special Termination Benefits | Organizational Design Initiative | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Organizational design initiative		8,000,000
Organizational design initiative, after tax		$ 5,000,000