Regulatory Matters Regulatory Matters - SPPC (Details) - Sierra Pacific Power Company [Member] - General Rate Case [Member] - Public Utilities Commission, Nevada [Member]	12 Months Ended
	Dec. 31, 2016 USD ($) MW
Schedule Of Regulatory Assets and Liabilities [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 0
Net Metering Capacity | MW	6
Electric Distribution [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 3,000,000
Gas Distribution [Member]
Schedule Of Regulatory Assets and Liabilities [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 2,000,000