Derivative Financial Instruments (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Derivative Asset, Current	[1]	$ 41	$ 18
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets Current	Other Assets Current
Derivative Asset, Noncurrent	[2]	$ 211	$ 130
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent	Regulated Entity Other Assets Noncurrent
Derivative Assets		$ 252	$ 148
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets	Assets
Derivative Liability, Current	[3]		$ 2
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]			Other Liabilities Current
Derivative Liability, Noncurrent	[4]	$ 2	$ 17
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent
Derivative Liability		$ 2	$ 19
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Liabilities And Stockholders Equity	Liabilities And Stockholders Equity
Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Current		$ 41	$ 18
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets Current	Other Assets Current
Derivative Asset, Noncurrent		$ 210	$ 130
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent	Regulated Entity Other Assets Noncurrent
Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Noncurrent		$ 2
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent
Derivative Liability, Current			$ 2
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]			Other Liabilities Current
Derivative Liability, Noncurrent		$ 1	$ 17
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	$ 0	$ 0
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets Current	Other Assets Current
Derivative Asset, Noncurrent	[2]	$ 0	$ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent	Regulated Entity Other Assets Noncurrent
Derivative Assets		$ 0	$ 0
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets	Assets
Derivative Liability, Current	[3]		$ 1
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]			Other Liabilities Current
Derivative Liability, Noncurrent	[4]	$ 2	$ 11
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent
Derivative Liability		$ 2	$ 12
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Liabilities And Stockholders Equity	Liabilities And Stockholders Equity
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Current		$ 0	$ 0
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets Current	Other Assets Current
Derivative Asset, Noncurrent		$ 0	$ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent	Regulated Entity Other Assets Noncurrent
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Noncurrent		$ 2
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent
Derivative Liability, Current			$ 1
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]			Other Liabilities Current
Derivative Liability, Noncurrent		$ 0	$ 11
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	$ 41	$ 18
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets Current	Other Assets Current
Derivative Asset, Noncurrent	[2]	$ 211	$ 130
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent	Regulated Entity Other Assets Noncurrent
Derivative Assets		$ 252	$ 148
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets	Assets
Derivative Liability, Current	[3]		$ 1
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]			Other Liabilities Current
Derivative Liability, Noncurrent	[4]	$ 0	$ 6
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent
Derivative Liability		$ 0	$ 7
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Liabilities And Stockholders Equity	Liabilities And Stockholders Equity
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Current		$ 41	$ 18
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Other Assets Current	Other Assets Current
Derivative Asset, Noncurrent		$ 210	$ 130
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent	Regulated Entity Other Assets Noncurrent
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Noncurrent		$ 0
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Regulated Entity Other Assets Noncurrent
Derivative Liability, Current			$ 1
Derivative Liability, Current, Statement of Financial Position [Extensible Enumeration]			Other Liabilities Current
Derivative Liability, Noncurrent		$ 1	$ 6
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent

[1] Current derivative assets are presented in other current assets in DESC’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets are presented in other deferred debits and other assets in DESC’s Consolidated Balance Sheets.

[3] Current derivative liabilities are presented in other current liabilities in DESC’s Consolidated Balance Sheets.

[4] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in DESC’s Consolidated Balance Sheets.