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Nuclear Insurance (Details) - NSP Minnesota - Nuclear Insurance
$ in Millions
 12 Months Ended
Dec. 31, 2023
USD ($)
Plant
Reactor
Nuclear Insurance [Abstract]  
Nuclear insurance coverage secured for the Company's public liability exposure $ 450
Nuclear insurance coverage exposure funded by the Secondary Financial Protection Program 15,800
Maximum assessments per reactor per accident $ 166
Number of owned and licensed reactors | Reactor 3
Maximum funding requirement per reactor for any one year $ 25
Number of nuclear plant sites operated by NSP-Minnesota | Plant 2
Maximum assessments for business interruption insurance each calendar year $ 15
Maximum assessment for property damage insurance NSP-Minnesota is subject to each calendar year 32
Maximum  
Nuclear Insurance [Abstract]  
Loss Contingency, Estimate of Possible Loss 16,200
Insurance coverage limits for NSP-Minnesota's nuclear plant sites 2,800
Business Interruption Insurance Coverage Provided by NEIL 490
Business Interruption Insurance Coverage Provided by NEIL - Prairie Island $ 420