Commitments and contingencies	3 Months Ended
Mar. 31, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and Contingencies We are party to claims and lawsuits arising out of our business and that of our consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual and statutory obligations. We accrue a liability for those contingencies when the incurrence of a loss is probable, and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. We do not accrue liabilities when the likelihood that the liability has been incurred is probable, but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, we disclose the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss, including, but not limited to, when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories. At March 31, 2026 and 2025, and December 31, 2025, we accrued contingent liabilities as a result of litigation, which have not been discounted, of $3.2 million, $3.4 million and $3.3 million, respectively. At March 31, 2026, we also recorded corresponding insurance receivables of $145,000. At March 31, 2025 and December 31, 2025, there were no corresponding insurance receivables recorded. The accruals are for contingencies, including litigation and environmental matters. Most of these claims and lawsuits are covered by insurance, thus our exposure is typically limited to our deductible amount. We will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred. Environmental matters Knife River Corporation - Northwest is a party to claims for the cleanup of a superfund site in Portland, Oregon. There were no material changes to the environmental matters that were previously reported in the audited financial statements and notes included in our 2025 Annual Report. Guarantees We have outstanding obligations to third parties where we have guaranteed our performance. These guarantees are related to contracts for contracting services and certain other guarantees. At March 31, 2026, the fixed maximum amounts guaranteed under these agreements aggregated to $11.5 million, all of which have no scheduled maturity date. Certain of the guarantees also have no fixed maximum amounts specified. There were no amounts outstanding under the previously mentioned guarantees at March 31, 2026. We have outstanding letters of credit to third parties related to insurance policies and other agreements. At March 31, 2026, the fixed maximum amounts guaranteed under these letters of credit aggregated to $51.8 million. At March 31, 2026, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $756,000 in 2026, $50.9 million in 2027, and $175,000 in 2028. There were no amounts outstanding under the previously mentioned letters of credit at March 31, 2026. In the normal course of business, we have surety bonds related to contracts for contracting services, reclamation obligations and insurance policies of its subsidiaries. In the event a subsidiary of Knife River does not fulfill a bonded obligation, we would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds are expected to expire within the next 12 months; however, we will likely continue to enter into surety bonds for our subsidiaries in the future. At March 31, 2026, approximately $990.4 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.

We are party to claims and lawsuits arising out of our business and that of our consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual and statutory obligations. We accrue a liability for those contingencies when the incurrence of a loss is probable, and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. We do not accrue liabilities when the likelihood that the liability has been incurred is probable, but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, we disclose the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss, including, but not limited to, when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories.

At March 31, 2026 and 2025, and December 31, 2025, we accrued contingent liabilities as a result of litigation, which have not been discounted, of $3.2 million, $3.4 million and $3.3 million, respectively. At March 31, 2026, we also recorded corresponding insurance receivables of $145,000. At March 31, 2025 and December 31, 2025, there were no corresponding insurance receivables recorded. The accruals are for contingencies, including litigation and environmental matters. Most of these claims and lawsuits are covered by insurance, thus our exposure is typically limited to our deductible amount. We will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred.

Knife River Corporation - Northwest is a party to claims for the cleanup of a superfund site in Portland, Oregon. There were no material changes to the environmental matters that were previously reported in the audited financial statements and notes included in our 2025 Annual Report.

We have outstanding obligations to third parties where we have guaranteed our performance. These guarantees are related to contracts for contracting services and certain other guarantees. At March 31, 2026, the fixed maximum amounts guaranteed under these agreements aggregated to $11.5 million, all of which have no scheduled maturity date. Certain of the guarantees also have no fixed maximum amounts specified. There were no amounts outstanding under the previously mentioned guarantees at March 31, 2026.

We have outstanding letters of credit to third parties related to insurance policies and other agreements. At March 31, 2026, the fixed maximum amounts guaranteed under these letters of credit aggregated to $51.8 million. At March 31, 2026, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $756,000 in 2026, $50.9 million in 2027, and $175,000 in 2028. There were no amounts outstanding under the previously mentioned letters of credit at March 31, 2026.

In the normal course of business, we have surety bonds related to contracts for contracting services, reclamation obligations and insurance policies of its subsidiaries. In the event a subsidiary of Knife River does not fulfill a bonded obligation, we would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds are expected to expire within the next 12 months; however, we will likely continue to enter into surety bonds for our subsidiaries in the future. At March 31, 2026, approximately $990.4 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.