Employee Benefit Plans (Benefit Obligation in Excess of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	$ 7,386	$ 5,728
Fair value of plan assets	5,340	4,571
Pension Benefits \| Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	0	0
Fair value of plan assets	0	0
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	470	359
Fair value of plan assets	356	299
Other Postretirement Plans \| Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	320	292
Fair value of plan assets	$ 299	$ 283

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

If aggregate disclosures are presented, the aggregate benefit obligation for plans with benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2417-114920

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- Definition

If aggregate disclosures are presented, the aggregate fair value of plan assets for plans with benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

+ References

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