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, 2014		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2014						$ 998	$ 0	$ 1,111	$ (111)	$ (2)
Net Income (Loss) Attributable to Parent	$ 1,901					68
Dividends, Common Stock, Cash						7	$ 0		7	0
Balance (shares) at Sep. 30, 2015		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2015						$ 1,059	$ 0	1,111	(50)	(2)
Stockholders' Equity, Other	$ 12	$ 0	$ 8	$ 0	$ 0
Balance (shares) at Dec. 31, 2015	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	$ 22,401					$ 1,076	$ 0	1,111	(35)	0
Net Income (Loss) Attributable to Parent	$ 2,062					65			65
Dividends, Common Stock, Cash						$ 45			45
Balance (shares) at Sep. 30, 2016	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Sep. 30, 2016	$ 24,354					$ 1,095	$ 0	$ 1,111	$ (15)	(1)
Stockholders' Equity, Other	$ (9)	$ 0	$ (1)	$ 0	$ 0	$ (1)				$ 1