Leases (Schedule of Lease Assets and Liabilities Recorded in Consolidated Balance Sheets) (Detail) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease assets	[1]	$ 18	$ 20
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		Total deferred debits and other assets	Total deferred debits and other assets
Finance lease assets	[2]	$ 6	$ 9
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		Utility plant, net	Utility plant, net
Total lease assets		$ 24	$ 29
Operating lease liabilities - current	[3]	$ 2	$ 3
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Other Liabilities, Current	Other Liabilities, Current
Operating lease liabilities - noncurrent	[4]	$ 17	$ 18
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities, Noncurrent	Liabilities, Noncurrent
Finance lease liabilities - current	[5]	$ 3	$ 4
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Liabilities, Current	Liabilities, Current
Finance lease liabilities - noncurrent		$ 4	$ 6
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Finance lease liabilities - noncurrent	Finance lease liabilities - noncurrent
Total lease liabilities		$ 26	$ 31

[1] Included in other deferred debits and other assets in the Consolidated Balance Sheets.

[2] Included in utility plant, net, in the Consolidated Balance Sheets, net of $17 million and $20 million of accumulated amortization at December 31, 2023 and December 31, 2022, respectively.

[3] Included in other current liabilities in the Consolidated Balance Sheets.

[4] Included in other deferred credits and other liabilities in the Consolidated Balance Sheets.

[5] Included in securities due within one year in the Consolidated Balance Sheets.