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, 2016		77,000,000		1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2016			$ 1,108	$ 0	$ 1,111	$ (2)	$ (1)
Net Income (Loss) Attributable to Parent	$ 2,198		85			85
Dividends, Common Stock, Cash			5	$ 0		5	0
Balance (shares) at Sep. 30, 2017		77,000,000		1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2017			$ 1,188	$ 0	1,111	78	(1)
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		$ 1,172	$ 0	1,111	62	(1)
Net Income (Loss) Attributable to Parent	$ 2,286		$ 76			76
Balance (shares) at Sep. 30, 2018	77,000,000	77,000,000	1,000	1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2018	$ 29,557		$ 1,248	$ 0	$ 1,111	$ 138	$ (1)