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, 2015		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2015						$ 1,076	$ 0	$ 1,111	$ (35)	$ 0
Net Income (Loss) Attributable to Parent	$ 1,026					27			27
Dividends, Common Stock, Cash						40	$ 0		40	0
Stockholders' Equity, Other	$ (10)	$ 0	$ (1)		$ 0
Balance (shares) at Jun. 30, 2016		77,000,000					1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2016						$ 1,063	$ 0	1,111	(48)	0
Balance (shares) at Dec. 31, 2016	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	$ 24,327					$ 1,108	$ 0	1,111	(2)	(1)
Net Income (Loss) Attributable to Parent	1,130					41			41
Dividends, Common Stock, Cash						5			5
Stockholders' Equity, Other	$ 23	$ 0	$ 21	$ (1)	$ 0	$ (1)			1
Balance (shares) at Jun. 30, 2017	77,000,000	77,000,000				1,000	1,000
Stockholders' Equity Attributable to Parent at Jun. 30, 2017	$ 25,740					$ 1,143	$ 0	$ 1,111	$ 33	$ (1)