Regulatory Matters - SPPC - Regulatory Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Total regulatory assets	$ 5,062	$ 3,963
Regulatory assets, current	1,319	544
Regulatory assets, noncurrent	3,743	3,419
Regulatory assets not earning a return on investment	$ 2,300	1,800
Deferred operating costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	10 years
Total regulatory assets	$ 83	103
Unrealized losses on regulated derivative contracts
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 112	157
SPPC
Regulatory Assets [Line Items]
Total regulatory assets	611	440
Regulatory assets, current	357	177
Regulatory assets, noncurrent	254	263
Regulatory assets not earning a return on investment	$ 143	158
SPPC | Deferred energy costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 277	107
SPPC | Natural disaster protection plan
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 69	62
SPPC | Merger costs from 1999 merger
Regulatory Assets [Line Items]
Regulatory asset, amortization period	24 years
Total regulatory assets	$ 63	66
SPPC | Employee benefit plans
Regulatory Assets [Line Items]
Regulatory asset, amortization period	8 years
Total regulatory assets	$ 57	46
SPPC | Deferred operating costs
Regulatory Assets [Line Items]
Regulatory asset, amortization period	7 years
Total regulatory assets	$ 35	31
SPPC | Unrealized losses on regulated derivative contracts
Regulatory Assets [Line Items]
Regulatory asset, amortization period	1 year
Total regulatory assets	$ 21	35
SPPC | Other
Regulatory Assets [Line Items]
Total regulatory assets	$ 89	$ 93