Consolidated Statements of Changes in Equity - NPC - USD ($) $ in Millions	Total	Additional Paid-in Capital	NPC	NPC Common Stock	NPC Additional Paid-in Capital	NPC Retained Earnings	NPC Accumulated Other Comprehensive Income (Loss)
Balance (shares) at Dec. 31, 2018				1,000
Balance at Dec. 31, 2018			$ 2,904	$ 0	$ 2,308	$ 600	$ (4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to parent	$ 2,950		264			264
Dividends declared			(371)			(371)
Other equity transactions	3
Balance (shares) at Dec. 31, 2019				1,000
Balance at Dec. 31, 2019			2,797	$ 0	2,308	493	(4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to parent	6,943		295			295
Dividends declared			(155)			(155)
Other equity transactions	$ 0	$ (1)	$ 2			1	1
Balance (shares) at Dec. 31, 2020	76,000,000		1,000	1,000
Balance at Dec. 31, 2020	$ 43,010		$ 2,939	$ 0	2,308	634	(3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to parent	5,790		303			303
Dividends declared			(213)			(213)
Other equity transactions	$ (1)		$ 1				1
Balance (shares) at Dec. 31, 2021	76,000,000		1,000	1,000
Balance at Dec. 31, 2021	$ 46,694		$ 3,030	$ 0	$ 2,308	$ 724	$ (2)