Consolidated Statements of Changes in Shareholder's Equity - NPC - USD ($) $ in Millions	Total	Additional Paid-in Capital	Retained Earnings	NPC	NPC Common Stock	NPC Additional Paid-in Capital	NPC Retained Earnings	NPC Accumulated Other Comprehensive Income (Loss)
Balance (shares) at Dec. 31, 2021					1,000
Balance at Dec. 31, 2021				$ 3,030	$ 0	$ 2,308	$ 724	$ (2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 2,721			298			298
Contributions				25		25
Other equity transactions	(6)	$ 1	$ (12)	1				1
Balance (shares) at Dec. 31, 2022					1,000
Balance at Dec. 31, 2022				3,354	$ 0	2,333	1,022	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	3,020			260			260
Dividends declared				(50)			(50)
Contributions				$ 400		400
Other equity transactions	$ (9)
Balance (shares) at Dec. 31, 2023	75,627,913			1,000	1,000
Balance at Dec. 31, 2023	$ 48,434			$ 3,964	$ 0	2,733	1,232	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	4,300			349			349
Dividends declared				(75)			(75)
Contributions				$ 210		210
Other equity transactions	$ (1)
Balance (shares) at Dec. 31, 2024	1			1,000	1,000
Balance at Dec. 31, 2024	$ 50,009			$ 4,448	$ 0	$ 2,943	$ 1,506	$ (1)