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, 2016		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2016						$ 2,972	$ 0	$ 2,308	$ 667	$ (3)
Net Income (Loss) Attributable to Parent	$ 1,130					87			87
Dividends, Common Stock, Cash						322			322
Stockholders' Equity, Other	$ 23	$ 0	$ 21	$ (1)	$ 0	(1)			(1)
Balance (shares) at Jun. 30, 2017		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2017						$ 2,738	$ 0	2,308	433	(3)
Balance (shares) at Dec. 31, 2017	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2017	$ 28,176					$ 2,678	$ 0	2,308	374	(4)
Net Income (Loss) Attributable to Parent	885					$ 64			64
Stockholders' Equity, Other	$ 4		$ 5
Balance (shares) at Jun. 30, 2018	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2018	$ 28,175					$ 2,742	$ 0	$ 2,308	$ 438	$ (4)