Recent Financing Transactions Recent Financing Transactions - SPPC (Details) - NVE Holdings [Member] - Sierra Pacific Power Company [Member] - Subsidiary Debt [Member] - USD ($) $ in Millions	Sep. 01, 2020	Apr. 01, 2020
Water facilities refunding revenue bonds, series 2016C, due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 30	$ 30
Debt Instrument, Interest Rate, Stated Percentage	0.625%
Gas facilities refunding revenue bonds, series 2016A, due 2031 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		59
Pollution Control Refunding Revenue Bonds, Series 2016A, due 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 20