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Regulatory Matters: Winter Storm Uri (Details) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2021 | Feb. 24, 2021 | Dec. 31, 2020
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | $ 802,257 |  | $ 278,258
Winter Storm Uri Incremental Costs in a Separately Tracked Mechanism |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 480,842 |  | 0
Deferred energy and gas costs |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 68,402 |  | 39,035
Deferred gas cost adjustments |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 17,066 |  | $ 3,200
Senior Unsecured Notes Due 2021 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Debt Instrument, Face Amount |  | $ 800,000 |
Winter Storm Uri |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Incremental Fuel, Purchased Power and Natural Gas Costs | 571,000 |  |
Regulatory assets | 558,825 |  |
Income Statement Impacts | 12,500 |  |
Winter Storm Uri | Winter Storm Uri Incremental Costs in a Separately Tracked Mechanism |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 480,842 |  |
Winter Storm Uri | Deferred energy and gas costs |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 27,166 |  |
Winter Storm Uri | Deferred gas cost adjustments |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 50,817 |  |
Winter Storm Uri | Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts) |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Income Statement Impacts | 700 |  |
Winter Storm Uri | Electric Utilities |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 50,966 |  |
Winter Storm Uri | Electric Utilities | Wholesale Power Margin Impacts |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Income Statement Impacts | 3,200 |  |
Winter Storm Uri | Electric Utilities | Non-recoverable Fuel Costs |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Income Statement Impacts | 2,100 |  |
Winter Storm Uri | Electric Utilities | Colorado Electric |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 25,500 |  |
Winter Storm Uri | Electric Utilities | South Dakota Electric |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 22,200 |  |
Winter Storm Uri | Electric Utilities | Wyoming Electric |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 3,266 |  |
Winter Storm Uri | Gas Utilities |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 507,859 |  |
Winter Storm Uri | Gas Utilities | Arkansas Gas |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 137,500 |  |
Winter Storm Uri | Gas Utilities | Colorado Gas |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 77,850 |  |
Winter Storm Uri | Gas Utilities | Iowa Gas |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 95,450 |  |
Winter Storm Uri | Gas Utilities | Kansas Gas |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 87,900 |  |
Winter Storm Uri | Gas Utilities | Nebraska Gas |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 79,750 |  |
Winter Storm Uri | Gas Utilities | Wyoming Gas |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Regulatory assets | 29,409 |  |
Winter Storm Uri | Gas Utilities | Black Hills Energy Services | Non-recoverable Fuel Costs |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Income Statement Impacts | 8,200 |  |
Winter Storm Uri | Power Generation | Operating Income (Loss) |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Income Statement Impacts | $ (1,700) |  |

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