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Regulatory Assets and Liabilities (Tables) | 12 Months Ended
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Dec. 31, 2024
Regulatory Assets and Liabilities Disclosure [Abstract] |
Regulatory Assets | Components of regulatory assets:
(Millions of Dollars) |  | See Note(s) |  | Remaining Amortization Period |  | Dec. 31, 2024 |  | Dec. 31, 2023
Regulatory Assets |  |  |  |  |  | Current |  | Noncurrent |  | Current |  | Noncurrent
Pension and retiree medical obligations |  | 11 |  | Various |  | $ | 39 |  |  | $ | 1,167 |  |  | $ | 27 |  |  | $ | 1,106 |
Net AROs |  | 1, 12 |  | Various |  | — |  |  | 387 |  |  | — |  |  | 316 |
Recoverable deferred taxes on AFUDC |  |  |  | Plant lives |  | — |  |  | 368 |  |  | — |  |  | 332 |
Depreciation differences |  |  |  | Various |  | 17 |  |  | 250 |  |  | 17 |  |  | 189 |
Excess deferred taxes — TCJA |  | 7 |  | Various |  | 10 |  |  | 184 |  |  | 10 |  |  | 198 |
MISO capacity revenue tracker |  |  |  | One to two years |  | 63 |  |  | 45 |  |  | 36 |  |  | 26 |
Environmental remediation costs |  | 1, 12 |  | Various |  | 13 |  |  | 39 |  |  | 15 |  |  | 94 |
Prairie Island extended power uprate |  |  |  | 10 years |  | 4 |  |  | 34 |  |  | 4 |  |  | 38 |
Conservation programs (a) |  | 1 |  | One to two years |  | 20 |  |  | 30 |  |  | 19 |  |  | 54 |
Purchased power contract costs |  |  |  | Term of related contract |  | 5 |  |  | 28 |  |  | 4 |  |  | 40 |
Benson biomass PPA termination and asset purchase |  |  |  | Four years |  | 10 |  |  | 26 |  |  | 10 |  |  | 36 |
Deferred natural gas, electric, steam energy/fuel costs |  |  |  | One to two years |  | 99 |  |  | 25 |  |  | 239 |  |  | 80 |
Sales true-up and revenue decoupling |  |  |  | Various |  | 60 |  |  | 23 |  |  | 7 |  |  | 33 |
Nuclear refueling outage costs |  | 1 |  | One to two years |  | 51 |  |  | 20 |  |  | 43 |  |  | 19 |
Gas pipeline inspection and remediation costs |  |  |  | One to two years |  | 47 |  |  | 9 |  |  | 40 |  |  | 25 |
Renewable resources and environmental initiatives |  |  |  | One to two years |  | 34 |  |  | 4 |  |  | 38 |  |  | 5 |
Other |  |  |  | Various |  | 89 |  |  | 210 |  |  | 102 |  |  | 207 |
Total regulatory assets |  |  |  |  |  | $ | 561 |  |  | $ | 2,849 |  |  | $ | 611 |  |  | $ | 2,798 |
(a)Includes costs for conservation programs, as well as incentives allowed in certain jurisdictions.
Regulatory Liabilities | Components of regulatory liabilities:
(Millions of Dollars) |  | See Note(s) |  | Remaining Amortization Period |  | Dec. 31, 2024 |  | Dec. 31, 2023
Regulatory Liabilities |  |  |  |  |  | Current |  | Noncurrent |  | Current |  | Noncurrent
Deferred income tax adjustments and TCJA refunds (a) |  | 7 |  | Various |  | $ | 7 |  |  | $ | 2,888 |  |  | $ | 7 |  |  | $ | 3,015 |
Plant removal costs |  | 1, 12 |  | Various |  | — |  |  | 2,208 |  |  | — |  |  | 1,984 |
Effects of regulation on employee benefit costs (b) |  | 11 |  | Various |  | — |  |  | 259 |  |  | — |  |  | 253 |
Renewable resources and environmental initiatives |  |  |  | Various |  | 16 |  |  | 232 |  |  | 9 |  |  | 188 |
Net AROs (c) |  |  |  | Various |  | — |  |  | 161 |  |  | — |  |  | 90 |
ITC deferrals |  | 1 |  | Various |  | — |  |  | 70 |  |  | 1 |  |  | 60 |
IRA deferral |  |  |  | One to three years |  | 3 |  |  | 37 |  |  | — |  |  | — |
Deferred natural gas, electric, steam energy/fuel costs |  |  |  | One to two years |  | 480 |  |  | 12 |  |  | 220 |  |  | — |
Contract valuation adjustments (d) |  | 1, 10 |  | Less than one year |  | 89 |  |  | — |  |  | 56 |  |  | — |
Conservation programs (e) |  | 1 |  | Less than one year |  | 52 |  |  | — |  |  | 47 |  |  | — |
Other |  |  |  | Various |  | 205 |  |  | 143 |  |  | 188 |  |  | 237 |
Total regulatory liabilities (f) |  |  |  |  |  | $ | 852 |  |  | $ | 6,010 |  |  | $ | 528 |  |  | $ | 5,827 |
(a)Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA. (b)Includes regulatory amortization and certain 2018 TCJA benefits approved by the CPUC to offset the PSCo prepaid pension asset. (c)Includes amounts recorded for future recovery of AROs, less amounts recovered through nuclear decommissioning accruals and gains from decommissioning investments. (d)Includes the fair value of FTR instruments utilized/intended to offset the impacts of transmission system congestion. (e)Includes costs for conservation programs, as well as incentives allowed in certain jurisdictions.. (f)Revenue subject to refund of $3 million and $187 million for 2024 and 2023, respectively, is included in other current liabilities.

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- Definition Tabular disclosure of assets that are created when regulatory agencies permit public utilities to defer certain costs included in rate-setting to the balance sheet. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478742/980-340-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 715 -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478574/980-715-50-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478742/980-340-50-2 + Details
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- Definition Tabular disclosure of regulatory liabilities. Detailed information about liabilities that result from rate actions of a regulator. Rate actions of a regulator can impose a liability on a regulated enterprise resulting in a regulatory liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 405 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477571/980-405-25-1 + Details
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