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Discontinued Operations and Disposal Groups (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | --- | ---
Apr. 25, 2023 | Sep. 30, 2023 | Sep. 30, 2023 | Sep. 30, 2022 | May 31, 2023 | Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Discontinued Operations Pro Rata Distribution |  |  |  |  | 90.00% |
Retained Shares Ownership Percentage |  |  |  |  | 10.00% |
Long-term debt |  | $ 2,341,147 | $ 2,341,147 | $ 2,278,730 |  | $ 2,365,667
Repayments of Long-term Debt |  |  | $ 434,994 | 0 |  |
Treasury Stock, Shares, Retired |  | 538,921 | 538,921 |  |  |
Restructuring and Related Cost, Incurred Cost |  | $ 1,000 | $ 47,100 |  |  |
Retained Shares [Abstract] |  |  |  |  | 5,700,000 |
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | Knife River Corporation | Cash Received, TSA |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Discontinued Operation, Amount of Continuing Cash Flows after Disposal |  | 1,300 | 1,900 |  |  |
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | Knife River Corporation | Cash Paid, TSA |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Discontinued Operation, Amount of Continuing Cash Flows after Disposal |  | 407 | 684 |  |  |
Knife River Corporation |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Repayments of Long-term Debt | $ 825,000 |  |  |  |  |
Senior Notes |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Long-term debt |  | $ 1,757,000 | $ 1,757,000 | $ 1,847,000 |  | $ 1,848,500
Senior Notes | Knife River Corporation |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Long-term debt | 425,000 |  |  |  |  |
Revolving Credit Facility | Knife River Corporation |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Long-term debt | 350,000 |  |  |  |  |
Term Loan Agreement | Knife River Corporation |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Long-term debt | $ 275,000 |  |  |  |  |

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