Supplemental Cash Flow Disclosures - SPPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Cash Flow Statements, Captions [Line Items]
Interest paid, net of amounts capitalized	$ 1,673	$ 1,764	$ 1,585
Accruals related to property, plant and equipment additions	547	718	1,143
Sierra Pacific Power Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Interest paid, net of amounts capitalized	47	54	54
Accruals related to property, plant and equipment additions	15	24	31
Capital and Financial Lease Obligations Incurred	$ 0	$ 13	$ 1