Employee Benefit Plans (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jan. 31, 2017	Mar. 31, 2017	Mar. 31, 2016
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
Dominion Questar Corporation | Capital Contribution to Dominion Questar to Fund Pension Contributions
Defined Benefit Plan Disclosure [Line Items]
Contribution to qualified pension plan	$ 75,000,000
Medical Coverage for Local 69 retirees
Defined Benefit Plan Disclosure [Line Items]
Retirement age		65 years
Decrease in accumulated postretirement benefit obligation		$ 73,000,000
Discount rate percentage		4.30%
Charge recorded from plan amendment and remeasurement		$ 7,000,000
Charge recorded from plan amendment and remeasurement, after tax		4,000,000
Virginia Electric and Power Company
Defined Benefit Plan Disclosure [Line Items]
Contribution to qualified pension plan		445,000,000	$ 0
Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined benefit pension plans and OPEB plans		0
Contribution to qualified pension plan		7,000,000	0
Expected contribution to voluntary employees' beneficiary association		12,000,000
Dominion Gas Holdings, LLC | Medical Coverage for Local 69 retirees
Defined Benefit Plan Disclosure [Line Items]
Decrease in accumulated postretirement benefit obligation		61,000,000
Charge recorded from plan amendment and remeasurement		6,000,000
Charge recorded from plan amendment and remeasurement, after tax		$ 4,000,000
Special Termination Benefits | Organizational Design Initiative
Defined Benefit Plan Disclosure [Line Items]
Organizational design initiative			70,000,000
Organizational design initiative, after tax			43,000,000
Special Termination Benefits | Organizational Design Initiative | Virginia Electric and Power Company
Defined Benefit Plan Disclosure [Line Items]
Organizational design initiative			40,000,000
Organizational design initiative, after tax			25,000,000
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