Consolidated Statements of Changes in Equity - SPPC - USD ($) $ in Millions	Total	Common Stock [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	$ 513		34			34
Balance (shares) at Mar. 31, 2018		77,000,000		1,000
Stockholders' Equity Attributable to Parent at Mar. 31, 2018			$ 1,206	$ 0	1,111	96	(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	$ 622		$ 22			22
Balance (shares) at Mar. 31, 2019	77,000,000	77,000,000	1,000	1,000
Stockholders' Equity Attributable to Parent at Mar. 31, 2019	$ 30,036		$ 1,286	$ 0	$ 1,111	$ 175	$ 0