Leases (Summary of Total Lease Cost) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2019
Finance lease cost:
Finance lease cost, Amortization	$ 7	$ 14
Finance lease cost, Interest	1	3
Operating lease cost	20	64
Short-term lease cost	7	20
Variable lease cost	1	4
Total lease cost	36	105
Virginia Electric and Power Company
Finance lease cost:
Operating lease cost	10	31
Short-term lease cost	3	7
Variable lease cost	1	2
Total lease cost	14	40
Dominion Energy Gas Holdings, LLC
Finance lease cost:
Operating lease cost	3	10
Short-term lease cost	2	5
Total lease cost	$ 5	$ 15

Amount of interest expense on finance lease liability.

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-Section 50
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Amount of amortization expense attributable to right-of-use asset from finance lease.

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Amount of lease cost recognized by lessee for lease contract.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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