Consolidated Statements of Changes in Equity - SPPC - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income, Net [Member]	Sierra Pacific Power Company [Member]	Sierra Pacific Power Company [Member] Common Stock [Member]	Sierra Pacific Power Company [Member] Additional Paid-in Capital [Member]	Sierra Pacific Power Company [Member] Retained Earnings [Member]	Sierra Pacific 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						$ 1,172	$ 0	$ 1,111	$ 62	$ (1)
Net Income (Loss) Attributable to Parent	$ 2,286					76			76
Stockholders' Equity, Other	(5)	$ 0	$ (5)	$ 0	$ 0
Balance (shares) at Sep. 30, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2018						1,248	$ 0	1,111	138	(1)
Balance (shares) at Jun. 30, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2018						1,212	$ 0	1,111	102	(1)
Net Income (Loss) Attributable to Parent	1,401					35			35
Stockholders' Equity, Other	$ (1)	$ 0	0	0	0	1	$ 0	0	1
Balance (shares) at Sep. 30, 2018		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2018						$ 1,248	$ 0	1,111	138	(1)
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					$ 1,264	$ 0	1,111	153	0
Net Income (Loss) Attributable to Parent	2,443					80			80
Dividends, Common Stock, Cash						$ (46)			(46)
Stockholders' Equity, Other	$ 3	$ 0	0	(1)	0
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					$ 1,298	$ 0	1,111	187	0
Balance (shares) at Jun. 30, 2019		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2019						1,254	$ 0	1,111	143	0
Net Income (Loss) Attributable to Parent	1,137					$ 44			44
Stockholders' Equity, Other	$ 6	$ 0	$ 0	$ 1	$ 0
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					$ 1,298	$ 0	$ 1,111	$ 187	$ 0