Income Taxes - NPC - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of Income Tax Expense (Benefit) [Line Items]
Current	$ (1,442)	$ (1,449)	$ (1,778)
Deferred	(356)	(462)	650
Total	(1,699)	(1,916)	(1,132)
NPC
Components of Income Tax Expense (Benefit) [Line Items]
Current	(4)	(13)	37
Deferred	(74)	49	0
Investment tax credits	100	0	0
Total	$ 22	$ 36	$ 37