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AROs (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance $ 3,380 $ 3,151
Amounts Incurred 10 [1] 59 [2]
Amounts Settled (1)  
Accretion 154 148
Cash flow revisions (325) [3] 22 [4]
Ending balance 3,218 3,380
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member]    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Decommissioning fund investments 3,211 2,882
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | NSP Minnesota    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Decommissioning fund investments 3,200 2,900
Electric Plant Nuclear Production Decommissioning    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 2,160 2,056
Amounts Incurred 0 [1] 0 [2]
Amounts Settled 0  
Accretion 105 104
Cash flow revisions (158) [3] 0 [4]
Ending balance 2,107 2,160
Electric Plant Wind Production    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 514 478
Amounts Incurred 10 [1] 25 [2]
Amounts Settled 0  
Accretion 19 19
Cash flow revisions (17) [3] (8) [4]
Ending balance 526 514
Electric Plant Steam, Hydro and Other Production Asbestos    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 348 288
Amounts Incurred 0 [1] 34 [2]
Amounts Settled (1)  
Accretion 15 12
Cash flow revisions (1) [3] 14 [4]
Ending balance 361 348
Electric Plant Electric Distribution    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 48 47
Amounts Incurred 0 [1] 0 [2]
Amounts Settled 0  
Accretion 1 1
Cash flow revisions 0 [3] 0 [4]
Ending balance 49 48
Natural Gas Plant Gas Transmission and Distribution    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance [5] 307 279
Amounts Incurred 0 [1] 0 [2],[5]
Amounts Settled  
Accretion 14 12 [5]
Cash flow revisions (149) [3] 16 [4],[5]
Ending balance 172 307 [5]
Common and Other Property Common Miscellaneous    
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance 3 3
Amounts Incurred 0 [1] 0 [2]
Amounts Settled 0  
Accretion 0 0
Cash flow revisions 0 [3] 0 [4]
Ending balance $ 3 $ 3
[1] Amounts incurred relate to the Northern Wind farm placed in service in NSP-Minnesota.
[2] Amounts incurred related to the wind farms placed in service in 2022 for NSP-Minnesota (Dakota Range and Rock Aetna) and steam production pond remediation costs for PSCo.
[3] In 2023, AROs were revised for changes in timing and estimates of cash flows. Revisions in wind and nuclear AROs were primarily incurred due to changes in useful lives. Changes in gas transmission and distribution AROs were a result of updated gas line mileage and number of services, as well as changes to inflation and discount rate assumptions.
[4] In 2022, AROs were revised for changes in timing and estimates of cash flows. Revisions in steam, hydro and other production AROs were primarily related to changes in cost estimates for remediation of ash containment facilities. Changes in gas transmission and distribution AROs were primarily related to changes in labor rates coupled with increased gas line mileage and number of services.
[5] Prior periods have been reclassified to conform with current year presentation.