Leases (Weighted Average Remaining Lease Term and Weighted Discounted Rate for Finance and Operating Leases) (Detail)	Sep. 30, 2019
Lessee Lease Disclosure [Line Items]
Weighted average remaining lease term - finance leases	6 years
Weighted average remaining lease term - operating leases	21 years
Weighted average discount rate - finance leases	4.36%
Weighted average discount rate - operating leases	4.58%
Virginia Electric and Power Company
Lessee Lease Disclosure [Line Items]
Weighted average remaining lease term - finance leases	6 years
Weighted average remaining lease term - operating leases	17 years
Weighted average discount rate - finance leases	4.65%
Weighted average discount rate - operating leases	4.51%
Dominion Energy Gas Holdings, LLC
Lessee Lease Disclosure [Line Items]
Weighted average remaining lease term - finance leases	6 years
Weighted average remaining lease term - operating leases	9 years
Weighted average discount rate - finance leases	4.55%
Weighted average discount rate - operating leases	4.43%

Lessee, lease, disclosure.

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- Definition

Weighted average discount rate for finance lease calculated at point in time.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
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Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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Weighted average discount rate for operating lease calculated at point in time.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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