Recent Financing Transactions - SPPC (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Apr. 29, 2022	Mar. 31, 2022	Mar. 31, 2021
Debt Instrument [Line Items]
Repayments of subsidiary debt		$ 193	$ 26
NV Energy loan, payable upon demand | SPPC | Unsecured Debt | Subsequent Event
Debt Instrument [Line Items]
Face amount	$ 200
NV Energy loan, payable upon demand | SPPC | Unsecured Debt | Subsequent Event | London Interbank Offered Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
Water facilities refunding revenue bonds, series 2016C, due 2036 | SPPC | Subsidiary Debt | Subsequent Event
Debt Instrument [Line Items]
Repayments of subsidiary debt	$ 30
Water facilities refunding revenue bonds, series 2016D, due 2036 | SPPC | Subsidiary Debt | Subsequent Event
Debt Instrument [Line Items]
Repayments of subsidiary debt	25
Water facilities refunding revenue bonds, series 2016E, due 2036 | SPPC | Subsidiary Debt | Subsequent Event
Debt Instrument [Line Items]
Repayments of subsidiary debt	25
Water facilities refunding revenue bonds, series 2016F, due 2036 | SPPC | Subsidiary Debt | Subsequent Event
Debt Instrument [Line Items]
Repayments of subsidiary debt	75
Water facilities refunding revenue bonds, series 2016G, due 2036 | SPPC | Subsidiary Debt | Subsequent Event
Debt Instrument [Line Items]
Repayments of subsidiary debt	20
Pollution Control Refunding Revenue Bonds, 1.850%, Series 2016B, due 2029 | SPPC | Subsidiary Debt | Subsequent Event
Debt Instrument [Line Items]
Repayments of subsidiary debt	$ 30