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Recent Financing Transactions Recent Financing Transactions - NPC (Details) - Nevada Power Company [Member] - NVE Holdings [Member] - USD ($)
$ in Millions
May 31, 2019
Jan. 31, 2019
NPC General and Refunding Mortgage Notes, Series CC [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Face Amount   $ 500
Debt Instrument, Interest Rate, Stated Percentage   3.70%
NPC General and Refunding Mortgage Notes, Series V [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Stated Percentage   7.10%
Debt Instrument, Repurchase Amount   $ 500
Line of Credit [Member] | Secured credit facility, $400 million, expiring June 2022 [Member]    
Debt Instrument [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity $ 400