Leases (Schedule of Lease Assets and Liabilities Recorded in Consolidated Balance Sheets) (Detail) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease assets	[1]	$ 20	$ 19
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]	$ 9	$ 13
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		Utility plant, net	Utility plant, net
Total lease assets		$ 29	$ 32
Operating lease liabilities - current	[3]	$ 3	$ 2
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Other Liabilities Current	Other Liabilities Current
Operating lease liabilities - noncurrent	[4]	$ 18	$ 17
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities Noncurrent	Liabilities Noncurrent
Finance lease liabilities - current	[5]	$ 4	$ 5
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Liabilities Current	Liabilities Current
Finance lease liabilities - noncurrent		$ 6	$ 10
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Finance lease liabilities - noncurrent	Finance lease liabilities - noncurrent
Total lease liabilities		$ 31	$ 34

[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 $20 million and $20 million of accumulated amortization at December 31, 2022 and December 31, 2021, 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.