Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015
Accounting Policy [Line Items]
Capitalized Interest Costs, Including Allowance for Funds Used During Construction		$ 100	$ 80	$ 66
Accrued unbilled revenue		$ 462	564
Percentage of fuel currently subject to deferred fuel accounting		84.00%
Accounts payable for checks outstanding		$ 27	42
Margin deposit assets		16	287
Margin liabilities			34
Virginia Electric and Power Company
Accounting Policy [Line Items]
Accrued unbilled revenue		333	407
Income tax receivable			225
Noncurrent income tax payable			38
Accounts payable for checks outstanding		11	20
Margin deposit assets			6
Capitalized interest costs		30	39	33
AFUDC related to projects		19	8	32
Dominion Gas Holdings, LLC
Accounting Policy [Line Items]
Accrued unbilled revenue		98	127
Income tax receivable			96
Accounts payable for checks outstanding		7	9
Capitalized interest costs		1	1	$ 5
Inventory under LIFO method		24	12
Amount exceeded on LIFO basis		109	98
Federal | IRS | Virginia Electric and Power Company
Accounting Policy [Line Items]
Income taxes payable		9
Federal | IRS | Tax Year 2014 | Virginia Electric and Power Company
Accounting Policy [Line Items]
Refund received for 2014 federal income tax payments	$ 229
Federal | IRS | Tax Year 2014 | Dominion Gas Holdings, LLC
Accounting Policy [Line Items]
Refund received for 2014 federal income tax payments	$ 93
State | Virginia Electric and Power Company
Accounting Policy [Line Items]
Income taxes payable		1
Income tax receivable		10
Noncurrent income taxes receivable		14	13
Noncurrent income tax payable		2
State | Dominion Gas Holdings, LLC
Accounting Policy [Line Items]
Income taxes payable		1	14
Income tax receivable		4
Noncurrent income taxes receivable			20
Noncurrent income tax payable		22	$ 7
Affiliated Entity | Virginia Electric and Power Company
Accounting Policy [Line Items]
Affiliated receivable for federal income tax payments expected to be refunded		296
Affiliated Entity | Dominion Gas Holdings, LLC
Accounting Policy [Line Items]
Affiliated receivable for federal income tax payments expected to be refunded		$ 91
Merchant Solar Projects | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Accounting Policy [Line Items]
SunEdison's ownership interest in merchant solar projects		33.00%			33.00%