Regulatory Matters - SPPC - Regulatory Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 6,818	$ 7,369
Regulatory liabilities, noncurrent	$ 6,644	7,070
Cost of removal
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	26 years
Total regulatory liabilities	$ 2,741	2,578
Other
Regulatory Liabilities [Line Items]
Total regulatory liabilities	289	446
SPPC
Regulatory Liabilities [Line Items]
Total regulatory liabilities	439	455
Regulatory liabilities, current	15	19
Regulatory liabilities, noncurrent	424	436
SPPC | Deferred income taxes
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 206	223
SPPC | Cost of removal
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	31 years
Total regulatory liabilities	$ 211	200
SPPC | Other
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 22	$ 32