Rate and Other Regulatory Matters (Schedule of Regulatory Liabilities) (Detail) - USD ($) $ in Millions		Jun. 30, 2025	Dec. 31, 2024
Regulatory Liabilities
Regulatory liability, current		$ 193	$ 201
Regulatory liability, noncurrent		2,341	2,488
Total regulatory liabilities		2,534	2,689
Monetization Of Guaranty Settlement [Member]
Regulatory Liabilities
Regulatory liability, current	[1]	67	67
Regulatory liability, noncurrent	[1]	535	568
Income Taxes Refundable Through Future Rates [Member]
Regulatory Liabilities
Regulatory liability, current	[2]	19	24
Regulatory liability, noncurrent	[2]	829	820
Asset Removal Costs [Member]
Regulatory Liabilities
Regulatory liability, noncurrent	[3]	599	598
Reserve For Refunds To Electric Utility Customers [Member]
Regulatory Liabilities
Regulatory liability, current	[4]	56	73
Regulatory liability, noncurrent	[4]	139	161
Derivatives [Member]
Regulatory Liabilities
Regulatory liability, current	[5]	36	27
Regulatory liability, noncurrent	[5]	234	328
Other Regulatory Liability [Member]
Regulatory Liabilities
Regulatory liability, current		15	10
Regulatory liability, noncurrent		$ 5	$ 13

[1] Represents proceeds related to the monetization of the Toshiba Settlement. In accordance with the SCANA Merger Approval Order, this balance, net of amounts that may be required to satisfy liens, will be refunded to electric customers over a 20-year period ending in 2039.

[2] Includes (i) excess deferred income taxes arising from the remeasurement of deferred income taxes in connection with the enactment of the 2017 Tax Reform Act (certain of which are protected under normalization rules and will be amortized over the remaining lives of related property, and certain of which will be amortized to the benefit of customers over prescribed periods as instructed by regulators) and (ii) deferred income taxes arising from investment tax credits, offset by (iii) deferred income taxes that arise from utility operations that have not been included in customer rates (a portion of which relate to depreciation and are expected to be recovered over the remaining lives of the related property which may range up to 85 years).

[3] Represents estimated net collections through depreciation rates of amounts to be expended for the removal of assets in the future.

[4] Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited to customers over an estimated 11-year period effective February 2019 in connection with the SCANA Merger Approval Order.

[5] Represents changes in the fair value of derivatives, excluding separately presented interest rate hedges, that following settlement are expected to be recovered from or refunded to customers.