XML 77 R48.htm IDEA: XBRL DOCUMENT v3.24.0.1
Borrowings and Other Financing Instruments Bilateral Credit Agreement (Details) - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Short-term Debt [Line Items]    
Amount outstanding at period end $ 785 $ 813
Revolving Credit Facility [Member]    
Short-term Debt [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity [1] 3,550  
Letter of Credit    
Short-term Debt [Line Items]    
Amount outstanding at period end 44 $ 43
NSP Minnesota | Revolving Credit Facility [Member]    
Short-term Debt [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity [1] 700  
NSP Minnesota | Letter of Credit | Bilateral Credit Agreement [Member]    
Short-term Debt [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity 75  
Amount outstanding at period end $ 65  
[1] These credit facilities mature in September 2027.