v3.26.3
Borrowings and Other Financing Instruments Purchase of of Subsidiary First Mortgage Bonds (Details) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
NSP-Minnesota    
Debt Instrument [Line Items]    
Debt Instrument, Repurchased Face Amount $ 141 $ 190
Debt Instrument, Repurchase Amount 97 122
SPS    
Debt Instrument [Line Items]    
Debt Instrument, Repurchased Face Amount 158  
Debt Instrument, Repurchase Amount 112  
XCEL ENERGY INC [Member]    
Debt Instrument [Line Items]    
Gain (Loss) on Repurchase of Debt Instrument $ 84 $ 63