Employee Benefit Plans (Fair values of pension and post retirement plan assets by asset category) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		$ 6,166	$ 6,480	$ 6,113
Pension Benefits | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,467	1,510	1,403
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,382	1,402	1,315
Other Postretirement Plans | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		283	288	$ 273
Collective Bargaining Agreement | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4,082	4,201
Total recorded at NAV	[1]	2,074	2,268
Pension plan assets by asset category	[2]	6,156	6,469
Pending sales of securities		112	31
Net accrued income		16	18
Pending purchases of securities		118	38
Collective Bargaining Agreement | Pension Benefits | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		16	38
Collective Bargaining Agreement | Pension Benefits | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,178	1,313
Collective Bargaining Agreement | Pension Benefits | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		475	530
Collective Bargaining Agreement | Pension Benefits | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		286	234
Collective Bargaining Agreement | Pension Benefits | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		493	403
Collective Bargaining Agreement | Pension Benefits | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[1]	330	360
Total recorded at NAV	[1],[3]	1,200	1,235
John Hancock insurance contracts held		330	360
Collective Bargaining Agreement | Pension Benefits | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		712	711
Collective Bargaining Agreement | Pension Benefits | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		358	416
Collective Bargaining Agreement | Pension Benefits | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		74	70
Collective Bargaining Agreement | Pension Benefits | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		70	86
Collective Bargaining Agreement | Pension Benefits | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		90	40
Collective Bargaining Agreement | Pension Benefits | Real estate-REITs | Real estate-Partnerships
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[1]	153	209
Collective Bargaining Agreement | Pension Benefits | Other alternative investments: | Private equity
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[3]	465	518
Collective Bargaining Agreement | Pension Benefits | Other alternative investments: | Debt
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[3]	170	144
Collective Bargaining Agreement | Pension Benefits | Other alternative investments: | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[1]	86	162
Collective Bargaining Agreement | Pension Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2,667	2,668
Collective Bargaining Agreement | Pension Benefits | Level 1 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		16	13
Collective Bargaining Agreement | Pension Benefits | Level 1 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,178	1,313
Collective Bargaining Agreement | Pension Benefits | Level 1 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		475	530
Collective Bargaining Agreement | Pension Benefits | Level 1 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		286	234
Collective Bargaining Agreement | Pension Benefits | Level 1 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		493	403
Collective Bargaining Agreement | Pension Benefits | Level 1 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[1]	0	0
Collective Bargaining Agreement | Pension Benefits | Level 1 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		40	45
Collective Bargaining Agreement | Pension Benefits | Level 1 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		60	74
Collective Bargaining Agreement | Pension Benefits | Level 1 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		20	10
Collective Bargaining Agreement | Pension Benefits | Level 1 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		9	6
Collective Bargaining Agreement | Pension Benefits | Level 1 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		90	40
Collective Bargaining Agreement | Pension Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1,415	1,533
Collective Bargaining Agreement | Pension Benefits | Level 2 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	25
Collective Bargaining Agreement | Pension Benefits | Level 2 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 2 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 2 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 2 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 2 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[1]	330	360
Collective Bargaining Agreement | Pension Benefits | Level 2 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		672	666
Collective Bargaining Agreement | Pension Benefits | Level 2 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		298	342
Collective Bargaining Agreement | Pension Benefits | Level 2 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		54	60
Collective Bargaining Agreement | Pension Benefits | Level 2 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		61	80
Collective Bargaining Agreement | Pension Benefits | Level 2 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[1]	0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Level 3 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		970	979
Total recorded at NAV	[3]	494	529
Pension plan assets by asset category	[4]	1,464	1,508
Pending sales of securities		27	7
Net accrued income		4
Pending purchases of securities		28	9
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4	9
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		280	306
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		113	124
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		68	54
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		117	94
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]	78	84
Total recorded at NAV	[3],[5]	286	288
John Hancock insurance contracts held		78	84
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		169	166
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		85	97
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		18	16
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		16	20
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		22	9
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Real estate-REITs | Real estate-Partnerships
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[3]	36	48
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Other alternative investments: | Private equity
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[3]	111	121
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Other alternative investments: | Debt
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[3]	40	34
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Other alternative investments: | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[3]	21	38
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		634	621
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4	3
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		280	306
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		113	124
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		68	54
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		117	94
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]	0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		9	11
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		14	17
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		5	2
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2	1
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 1 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		22	9
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		336	358
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	6
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]	78	84
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		160	155
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		71	80
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		13	14
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		14	19
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 2 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[5]	0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Pension Benefits | Dominion Gas Holdings, LLC | Level 3 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		752	762
Total recorded at NAV	[6]	630	640
Pension plan assets by asset category	[6]	1,382	1,402
Collective Bargaining Agreement | Other Postretirement Plans | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2	8
Collective Bargaining Agreement | Other Postretirement Plans | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		468	514
Collective Bargaining Agreement | Other Postretirement Plans | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		26	28
Collective Bargaining Agreement | Other Postretirement Plans | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		107	102
Collective Bargaining Agreement | Other Postretirement Plans | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		27	21
Collective Bargaining Agreement | Other Postretirement Plans | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[7]	18	19
Total recorded at NAV	[6],[7]	543	536
John Hancock insurance contracts held		18	19
Collective Bargaining Agreement | Other Postretirement Plans | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		39	38
Collective Bargaining Agreement | Other Postretirement Plans | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		20	22
Collective Bargaining Agreement | Other Postretirement Plans | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4	4
Collective Bargaining Agreement | Other Postretirement Plans | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		4	4
Collective Bargaining Agreement | Other Postretirement Plans | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		37	2
Collective Bargaining Agreement | Other Postretirement Plans | Real estate-REITs | Real estate-Partnerships
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	14	19
Collective Bargaining Agreement | Other Postretirement Plans | Other alternative investments: | Private equity
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	54	58
Collective Bargaining Agreement | Other Postretirement Plans | Other alternative investments: | Debt
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	14	18
Collective Bargaining Agreement | Other Postretirement Plans | Other alternative investments: | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	5	9
Collective Bargaining Agreement | Other Postretirement Plans | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		673	676
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1	1
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		468	514
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		26	28
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		107	102
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		27	21
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[7]	0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		2	3
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		3	4
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1	1
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 1 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		37	2
Collective Bargaining Agreement | Other Postretirement Plans | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		79	86
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		1	7
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[7]	18	19
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		37	35
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		17	18
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		3	3
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		3	4
Collective Bargaining Agreement | Other Postretirement Plans | Level 2 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Non-U.S. equity: | Other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value	[7]	0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Fixed Income: | Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Fixed Income: | U.S. Treasury securities and agency debentures
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Fixed Income: | State and municipal
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Fixed Income: | Other securities
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Level 3 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		137	141
Pension plan assets by asset category	[6]	283	288
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	2
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		102	113
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		24	26
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Common/collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6],[8]	132	129
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		11	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Real estate-REITs | Real estate-Partnerships
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	2	2
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Other alternative investments: | Private equity
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	11	12
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Other alternative investments: | Debt
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	1	4
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Other alternative investments: | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Total recorded at NAV	[6]	146	147
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		137	139
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		102	113
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		24	26
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 1 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		11	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	2
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	2
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 2 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 | Cash equivalents and other
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 | U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 | Non-U.S. equity: | Large Cap
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		0	0
Collective Bargaining Agreement | Other Postretirement Plans | Dominion Gas Holdings, LLC | Level 3 | Real estate-REITs | Real estate-REITs
Defined Benefit Plan Disclosure [Line Items]
Total recorded at fair value		$ 0	$ 0

[1] Common/collective trust funds include $330 million and $360 million of John Hancock insurance contracts held at December 31, 2015 and 2014, respectively. See below for a description of the individual investments included within this line item, and the nature and risk of each respective fund.

[2] Includes net assets related to pending sales of securities of $112 million, net accrued income of $16 million, and excludes net assets related to pending purchases of securities of $118 million at December 31, 2015. Includes net assets related to pending sales of securities of $31 million, net accrued income of $18 million, and excludes net assets related to pending purchases of securities of $38 million at December 31, 2014.

[3] These investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

[4] Includes net assets related to pending sales of securities of $27 million, net accrued income of $4 million, and excludes net assets related to pending purchases of securities of $28 million at December 31, 2015. Includes net assets related to pending sales of securities of $7 million, net accrued income of $4 million, and excludes net assets related to pending purchases of securities of $9 million at December 31, 2014.

[5] Common/collective trust funds include $78 million and $84 million of John Hancock insurance contracts held at December 31, 2015 and 2014, respectively. See below for a description of the individual investments included within this line item, and the nature and risk of each respective fund.

[6] These investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

[7] Common/collective trust funds include $18 million and $19 million of John Hancock insurance contracts held at December 31, 2015 and 2014, respectively. See below for a description of the individual investments included within this line item, and the nature and risk of each respective fund.

[8] See below for a description of the individual investments included within this line item, and the nature and risk of each respective fund.