Long-Term Debt (Based on Stated Maturity Dates Rather than Early Redemption Dates that Could be Elected by Instrument Holders) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
2017	$ 1,711
2018	3,295
2019	3,371
2020	1,719
2021	2,169
Thereafter	19,927
Total	$ 32,192
Weighted- average Coupon, 2017 (percentage)	3.13%
Weighted- average Coupon, 2018 (percentage)	3.62%
Weighted- average Coupon, 2019 (percentage)	3.09%
Weighted- average Coupon, 2020 (percentage)	2.07%
Weighted- average Coupon, 2021 (percentage)	3.12%
Weighted- average Coupon, Thereafter (percentage)	4.38%
Dominion Gas Holdings, LLC
Debt Instrument [Line Items]
2017	$ 0
2018	0
2019	450
2020	700
2021	0
Thereafter	2,413
Total	$ 3,563
Weighted- average Coupon, 2017 (percentage)
Weighted- average Coupon, 2018 (percentage)
Weighted- average Coupon, 2019 (percentage)	2.50%
Weighted- average Coupon, 2020 (percentage)	2.80%
Weighted- average Coupon, 2021 (percentage)
Weighted- average Coupon, Thereafter (percentage)	3.90%
Virginia Electric and Power Company
Debt Instrument [Line Items]
2017	$ 679
2018	850
2019	350
2020	0
2021	0
Thereafter	8,718
Total	$ 10,597
Weighted- average Coupon, 2017 (percentage)	5.47%
Weighted- average Coupon, 2018 (percentage)	4.17%
Weighted- average Coupon, 2019 (percentage)	5.00%
Weighted- average Coupon, 2020 (percentage)
Weighted- average Coupon, 2021 (percentage)
Weighted- average Coupon, Thereafter (percentage)	4.37%
Term Loans
Debt Instrument [Line Items]
2017	$ 268
2018	20
2019	321
2020	19
2021	19
Thereafter	308
Total	955
Unsecured Senior Notes
Debt Instrument [Line Items]
2017	1,368
2018	3,275
2019	2,500
2020	700
2021	900
Thereafter	16,122
Total	24,865
Unsecured Senior Notes \| Virginia Electric and Power Company
Debt Instrument [Line Items]
2017	604
2018	850
2019	350
2020	0
2021	0
Thereafter	7,940
Total	9,744
Tax-Exempt Financings
Debt Instrument [Line Items]
2017	75
2018	0
2019	0
2020	0
2021	0
Thereafter	880
Total	955
Tax-Exempt Financings \| Virginia Electric and Power Company
Debt Instrument [Line Items]
2017	75
2018	0
2019	0
2020	0
2021	0
Thereafter	778
Total	853
Unsecured Junior Subordinated Notes Payable to Affiliated Trusts
Debt Instrument [Line Items]
2017	0
2018	0
2019	0
2020	0
2021	0
Thereafter	10
Total	10
Unsecured Junior Subordinated Notes
Debt Instrument [Line Items]
2017	0
2018	0
2019	550
2020	0
2021	550
Thereafter	0
Total	1,100
Unsecured Junior Subordinated Notes
Debt Instrument [Line Items]
2017	0
2018	0
2019	0
2020	0
2021	0
Thereafter	1,907
Total	1,907
Remarketable Subordinated Notes
Debt Instrument [Line Items]
2017	0
2018	0
2019	0
2020	1,000
2021	700
Thereafter	700
Total	$ 2,400

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