Borrowings and Other Financing Instruments Long-Term Borrowings (Details) - Bonds [Member] $ in Millions	Jun. 30, 2023 USD ($)
PSCo | Series Due April 1, 2053
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 850
Debt Instrument, Interest Rate, Stated Percentage	5.25%
NSP-Wisconsin | Series Due April 1, 2052
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 125
Debt Instrument, Interest Rate, Stated Percentage	5.30%
NSP-Minnesota | Series Due May 15, 2053
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 800
NSP-Minnesota | Series Due May 15, 2023
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.10%