Leases (Summary of Total Lease Cost) (Detail) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Finance lease cost:
Finance lease cost, Amortization	$ 3
Finance lease cost, Interest	1
Operating lease cost	25
Short-term lease cost	6
Variable lease cost	2
Total lease cost	37
Virginia Electric and Power Company
Finance lease cost:
Operating lease cost	10
Short-term lease cost	2
Variable lease cost	1
Total lease cost	13
Dominion Energy Gas Holdings, LLC
Finance lease cost:
Operating lease cost	4
Short-term lease cost	1
Total lease cost	$ 5

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Amount of interest expense on finance lease liability.

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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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