Consolidated Statements of Changes in Equity - NPC - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income, Net [Member]	Nevada Power Company [Member]	Nevada Power Company [Member] Common Stock [Member]	Nevada Power Company [Member] Additional Paid-in Capital [Member]	Nevada Power Company [Member] Retained Earnings [Member]	Nevada Power Company [Member] Accumulated Other Comprehensive (Loss) Income, Net [Member]
Balance (shares) at Dec. 31, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2018						$ 2,904	$ 0	$ 2,308	$ 600	$ (4)
Net Income (Loss) Attributable to Parent	$ 2,443					240			240
Dividends, Common Stock, Cash						(95)			(95)
Balance (shares) at Sep. 30, 2019		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2019						3,049	$ 0	2,308	745	(4)
Stockholders' Equity, Other	3	$ 0	$ 0	$ (1)	$ 0
Balance (shares) at Jun. 30, 2019		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2019						2,884	$ 0	2,308	580	(4)
Net Income (Loss) Attributable to Parent	1,137					165			165
Balance (shares) at Sep. 30, 2019		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2019						$ 3,049	$ 0	2,308	745	(4)
Stockholders' Equity, Other	$ 6	$ 0	0	1	0
Balance (shares) at Dec. 31, 2019	0	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2019	$ 32,449					$ 2,797	$ 0	2,308	493	(4)
Net Income (Loss) Attributable to Parent	$ 4,628					273			273
Dividends, Common Stock, Cash						$ (85)			(85)
Balance (shares) at Sep. 30, 2020	0	76,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2020	$ 36,768					$ 2,986	$ 0	2,308	682	(4)
Stockholders' Equity, Other	0	$ 0	(1)	0	0	1			1
Balance (shares) at Jun. 30, 2020		76,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2020						2,792	$ 0	2,308	488	(4)
Net Income (Loss) Attributable to Parent	$ 2,842					$ 194			194
Balance (shares) at Sep. 30, 2020	0	76,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2020	$ 36,768					$ 2,986	$ 0	$ 2,308	$ 682	$ (4)
Stockholders' Equity, Other	$ 1	$ 0	$ 0	$ 0	$ 0