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, 2017		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2017						$ 2,678	$ 0	$ 2,308	$ 374	$ (4)
Net Income (Loss) Attributable to Parent	$ 2,286					228			228
Balance (shares) at Sep. 30, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2018						2,905	$ 0	2,308	601	(4)
Stockholders' Equity, Other	(5)	$ 0	$ (5)	$ 0	$ 0	(1)			(1)
Balance (shares) at Jun. 30, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2018						2,742	$ 0	2,308	438	(4)
Net Income (Loss) Attributable to Parent	1,401					164			164
Balance (shares) at Sep. 30, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2018						2,905	$ 0	2,308	601	(4)
Stockholders' Equity, Other	$ (1)	$ 0	0	0	0	$ (1)			(1)	0
Balance (shares) at Dec. 31, 2018	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2018	$ 29,593					$ 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	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2019	$ 31,608					$ 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	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2019	$ 31,608					$ 3,049	$ 0	$ 2,308	$ 745	$ (4)
Stockholders' Equity, Other	$ 6	$ 0	$ 0	$ 1	$ 0