Regulatory Matters - NPC - Regulatory Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 7,033	$ 6,818
Regulatory liabilities	$ 6,754	6,644
Cost of removal
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	27 years
Total regulatory liabilities	$ 2,918	2,741
Other
Regulatory Liabilities [Line Items]
Total regulatory liabilities	406	296
NPC
Regulatory Liabilities [Line Items]
Total regulatory liabilities	1,038	1,060
Regulatory liabilities, current	41	43
Regulatory liabilities	997	1,017
NPC | Deferred income taxes
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 510	525
NPC | Cost of removal
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	37 years
Total regulatory liabilities	$ 399	368
NPC | Earning sharing mechanism
Regulatory Liabilities [Line Items]
Regulatory liability, amortization period	4 years
Total regulatory liabilities	$ 77	115
NPC | Other
Regulatory Liabilities [Line Items]
Total regulatory liabilities	$ 52	$ 52