Significant Accounting Policies (Schedule of Supplemental Cash Flow Information) (Detail) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Significant noncash investing and financing activities:
Accrued capital expenditures	[1]	$ 374	$ 461
Accrued contributions to equity method affiliates	[1]	0	15
Leases	[1],[2]	75	45
Virginia Electric and Power Company
Significant noncash investing and financing activities:
Accrued capital expenditures	[3]	238	234
Leases	[3],[4]	$ 59	$ 26

[1] See Notes 16 and 17 for noncash financing activities related to derivative restructuring and the issuance of stock associated with the settlement of litigation and noncash investing activities related to property, plant and equipment conveyed to satisfy litigation, respectively.

[2] Includes $34 million and $42 million of financing leases at September 30, 2021 and 2020, respectively, and $41 million and $3 million of operating leases at September 30, 2021 and 2020, respectively.

[3] See Note 16 for noncash financing activities related to derivative restructuring.

[4] Includes $24 million and $26 million of financing leases at September 30, 2021 and 2020, respectively, and $35 million of operating leases at September 30, 2021.