Long-term Debt - SPPC - Narrative (Details) - USD ($) $ in Millions	Feb. 29, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Par value		$ 52,313
SPPC
Debt Instrument [Line Items]
Eligible property subject to lien of mortgages		5,000
SPPC
Debt Instrument [Line Items]
Par value		$ 1,302
Washoe County Series 2016F, due 2036 | SPPC | Subsequent event
Debt Instrument [Line Items]
Par value	$ 75
Stated rate	4.125%
Washoe County Series 2016B, due 2036 | SPPC | Subsequent event
Debt Instrument [Line Items]
Par value	$ 60
Stated rate	3.625%
Humboldt County Series 2016B, due 2029 | SPPC | Subsequent event
Debt Instrument [Line Items]
Par value	$ 30
Stated rate	3.55%
Washoe County Series 2016C, due 2036 | SPPC | Subsequent event
Debt Instrument [Line Items]
Par value	$ 30
Stated rate	4.125%
Humboldt County Series 2016A due 2029 | SPPC | Subsequent event
Debt Instrument [Line Items]
Par value	$ 20
Stated rate	3.55%
Washoe County Series 2016G, due 2036 | SPPC | Subsequent event
Debt Instrument [Line Items]
Par value	$ 20
Stated rate	3.625%