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Regulatory Matters: Regulatory Matters (Details) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2020
Regulatory assets | $ 480.1 | $ 653.0 |
Regulatory assets, current | (175.7) | (260.3) |
Regulatory assets, non-current | 304.4 | 392.7 |
Regulatory liabilities | 566.6 | 518.6 |
Regulatory liabilities, current | (98.9) | (46.0) |
Regulatory liabilities, non-current | $ 467.7 | 472.6 |
Maximum |  |  |
Gas Price Derivatives - Term of Contract | 2 years |  |
Deferred energy and gas costs |  |  |
Regulatory liabilities | $ 88.9 | 41.7 |
Employee benefit plans and related deferred taxes |  |  |
Regulatory liabilities | 36.2 | 38.9 |
Cost of removal |  |  |
Regulatory liabilities | 181.9 | 175.6 |
Excess deferred income taxes |  |  |
Regulatory liabilities | 247.1 | 254.8 |
Other regulatory liabilities |  |  |
Regulatory liabilities | 12.5 | 7.6 |
Storm Costs |  |  |
Regulatory assets | $ 199.6 | 348.0 |
Regulatory Asset, Amortization Period | 2 years 2 months 12 days |  |
Deferred energy and gas costs |  |  |
Regulatory assets | $ 55.1 | 72.6 |
Deferred gas cost adjustments |  |  |
Regulatory assets | 4.1 | 12.2 |
Gas price derivatives |  |  |
Regulatory assets | 5.1 | 8.8 |
Deferred taxes on AFUDC |  |  |
Regulatory assets | 7.1 | 7.3 |
Employee benefit plans and related deferred taxes |  |  |
Regulatory assets | 89.3 | 89.3 |
Environmental |  |  |
Regulatory assets | 2.9 | 1.3 |
Loss on reacquired debt |  |  |
Regulatory assets | 17.4 | 19.2 |
Deferred taxes on flow through accounting |  |  |
Regulatory assets | 74.7 | 69.5 |
Decommissioning costs |  |  |
Regulatory assets | 2.4 | 3.5 |
Regulatory Asset, Amortization Period |  |  | 3 years
Other regulatory assets |  |  |
Regulatory assets | $ 22.4 | $ 21.3 |

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- Definition Amortization period for the recovery of regulatory asset, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. + 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//1943274/2147481878/980-340-50-1 + Details
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