Acquisitions and Dispositions (Proposed Acquisition Of SCANA) (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended
	Oct. 31, 2018	Jan. 31, 2018
SCANA
Business Acquisition And Dispositions [Line Items]
Common stock agreed to issue		66.90%
Combination debt outstanding		$ 7,100
One-time rate credit to electric service customers, period within closing		90 days
Business combination, refund to customers		$ 575
Discount on existing customers		7.00%
Period to recognize reduction to SCE&G electric service customers bills		8 years
SCANA | Termination Fee Paid By Dominion to SCANA
Business Acquisition And Dispositions [Line Items]
Contract termination fee		$ 280
SCANA | Termination Fee Paid to Dominion
Business Acquisition And Dispositions [Line Items]
Contract termination fee		240
SCANA | Upfront Payment | Electric Service Customers
Business Acquisition And Dispositions [Line Items]
Business combination, liability incurred		1,300
SCANA | Subsequent Event
Business Acquisition And Dispositions [Line Items]
Business combination, refund to customers	$ 1,900
Discount on existing customers	14.00%
Period to provide refund to customer	20 years
V.C. Summer Units
Business Acquisition And Dispositions [Line Items]
Business combination cost related to exclusion from rate recovery		1,700
V.C. Summer Units | Subsequent Event
Business Acquisition And Dispositions [Line Items]
Business combination cost related to exclusion from rate recovery	$ 2,300
Columbia Energy
Business Acquisition And Dispositions [Line Items]
Business combination cost related to exclusion from rate recovery		$ 180
Columbia Energy | Subsequent Event
Business Acquisition And Dispositions [Line Items]
Business combination cost related to exclusion from rate recovery	$ 180