Regulatory Matters - NPC - Regulatory Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 7,369	$ 7,214
Regulatory liabilities, current	299	254
Regulatory liabilities	$ 7,070	6,960
Cost of removal
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	27 years
Total regulatory liabilities	$ 2,578	2,424
Other
Regulatory Liabilities [Line Items]
Total regulatory liabilities	446	484
NPC
Regulatory Liabilities [Line Items]
Total regulatory liabilities	1,138	1,149
Regulatory liabilities, current	45	49
Regulatory liabilities	1,093	1,100
NPC | Deferred income taxes
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 560	603
NPC | Cost of removal
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	31 years
Total regulatory liabilities	$ 358	348
NPC | Earning sharing mechanism
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	4 years
Total regulatory liabilities	$ 114	73
NPC | Other
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 106	$ 125