Regulatory Assets and Liabilities (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Regulatory Assets And Liabilities [Line Items]
Regulatory assets represented past expenditures not earning return	$ 131
Period expenditures expected to be recovered (years)	2 years
Virginia Electric and Power Company
Regulatory Assets And Liabilities [Line Items]
Regulatory assets represented past expenditures not earning return	$ 100
Dominion Gas Holdings, LLC
Regulatory Assets And Liabilities [Line Items]
Regulatory assets represented past expenditures not earning return	$ 29