Significant Accounting Policies (Schedule of Supplemental Cash Flow Information) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Significant noncash investing and financing activities:
Accrued capital expenditures		$ 425	$ 341
Leases	[1]	24	9
Virginia Electric and Power Company
Significant noncash investing and financing activities:
Accrued capital expenditures		252	262
Leases	[2]	$ 21	$ 1

[1] Includes $6 million and $2 million of financing leases at March 31, 2022 and 2021, respectively, and $18 million and $7 million of operating leases at March 31, 2022 and 2021, respectively.

[2] Includes $4 million and $1 million of financing leases at March 31, 2022 and 2021, respectively, and $17 million of operating leases at March 31, 2022