Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates: The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and judgments. These estimates and judgments affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities (if any) at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents include cash in banks and highly liquid investments with original maturities of three months or less.
Property, Plant and Equipment, Net	Property, Plant and Equipment, Net: Property, plant and equipment are initially recorded at cost. Depreciation, depletion and amortization are provided in amounts sufficient to amortize the cost of the assets, including assets recorded under finance leases, over their estimated useful lives using the straight-line method or the units-of-production method. Buildings and building improvements are depreciated over the life of the asset, which is generally 30 years. Estimated lives for machinery and equipment generally range from three to 15 years. The units-of-production method is used to amortize certain assets based on estimated recoverable tonnages. Repairs and maintenance costs are expensed when incurred, unless such costs extend the estimated useful life of the asset, in which case such costs are capitalized and depreciated. Asset retirement costs associated with asset retirement obligations are capitalized with the carrying amount of the related long-lived asset and depreciated over the asset's estimated useful life.
Royalty Interests in Oil and Natural Gas Properties	Royalty Interests in Oil and Natural Gas Properties: We follow the successful efforts method of accounting for royalty and mineral interests. Under this method, costs to acquire mineral and royalty interests in oil and natural gas properties are capitalized when incurred. Acquisitions of royalty interests of oil and natural gas properties are considered asset acquisitions and are recorded at cost. As an owner of mineral and royalty interests and not working interests, we are not required to make capital expenditures and did not make capital expenditures to convert proved undeveloped reserves from undeveloped to developed. Acquisition costs of proved royalty and mineral interests are amortized using the units of production method over the life of the property, which is estimated using proved reserves. For purposes of amortization, interests in oil and natural gas properties are grouped in a reasonable aggregation of properties with common geological structural features or stratigraphic condition. We review and evaluate our royalty interests in oil and natural gas properties for impairment when events or changes in circumstances indicate that the related carrying amounts may not be recoverable. Proved oil and gas properties are reviewed for impairment when events and circumstances indicate a potential decline in the fair value of such properties below the carrying value, such as a downward revision of the reserve estimates or lower commodity prices. When such events or changes in circumstances occur, we estimate the undiscounted future cash flows expected in connection with the properties and compare such future cash flows to the carrying amounts of the properties to determine if the carrying amounts are recoverable. If the carrying value of the properties is determined to not be recoverable based on the undiscounted cash flows, an impairment charge is recognized by comparing the carrying value to the estimated fair value of the properties.
Long-Lived Assets	Long-Lived Assets: We periodically evaluate long-lived assets for impairment when changes in circumstances or the occurrence of certain events indicate the carrying amount of an asset or asset group may not be recoverable. Upon identification of indicators of impairment, we evaluate the carrying value of the asset by comparing the estimated future undiscounted cash flows generated from the use of the asset or asset group and its eventual disposition with the asset's net carrying value. If the carrying value of an asset is considered impaired, an impairment charge is recorded for the amount that the carrying value of the long-lived asset or asset group exceeds its fair value. Fair value is estimated as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Identifying and assessing whether impairment indicators exist, or if events or changes in circumstances have occurred, including assumptions about future power plant dispatch levels, changes in future sales price, operating costs and other factors that impact anticipated revenue and customer demand, requires significant judgment. We determined that indicators of impairment existed at MLMC during the fourth quarter of 2023 and, as a result, MLMC's long-lived assets were reviewed for impairment. We assessed the recoverability of the MLMC asset group and determined that the assets were not fully recoverable when compared to the remaining future undiscounted cash flows from these assets. As a result, we estimated the fair value of the asset group which resulted in a non-cash, long-lived asset impairment charge of $65.9 million in 2023.
Self-insurance Liabilities	Self-insurance Liabilities: We are generally self-insured for medical claims, certain workers’ compensation claims and certain closed mine liabilities. An estimated provision for claims reported and for claims incurred but not yet reported under the self-insurance programs is recorded and revised periodically based on industry trends, historical experience and management judgment. In addition, industry trends are considered within management's judgment for valuing claims. Changes in assumptions for such matters as legal judgments and settlements, inflation rates, medical costs and actual experience could cause estimates to change in the near term.
Stock Compensation	Stock Compensation: We maintain a long-term incentive program that allow for the grant of shares of Class A common stock, subject to restrictions, as a means of retaining and rewarding selected employees for long-term performance and to increase their ownership in NACCO. Shares awarded under the plans are fully vested and entitle the stockholder to all rights of common stock ownership except that shares may not be assigned, pledged or otherwise transferred during the restriction period. In general, for shares awarded for years ended December 31, 2024 and December 31, 2023, the restriction period ends at the earliest of (i) three years after the participant's retirement date, (ii) three, five or ten years from the award date, or (iii) the participant's death or permanent disability. Pursuant to the plans, we issued 162,670 and 120,649 shares related to the years ended December 31, 2024 and 2023, respectively. After the issuance of these shares, there were 616,681 shares of Class A common stock available for issuance under these plans. Compensation expense related to these share awards was $5.2 million ($4.1 million net of tax) and $4.1 million ($3.3 million net of tax) for the years ended December 31, 2024 and 2023, respectively. Compensation expense represents fair value based on the market price of the shares of Class A common stock at the grant date. We also have a stock compensation plan for non-employee directors under which a portion of the annual retainer for each non-employee director is paid in restricted shares of Class A common stock. For the year ended December 31, 2024 and 2023, $110,000 ($150,000 for the Chairman) of the non-employee director's annual retainer of $175,000 ($250,000 for the Chairman) was paid in restricted shares of Class A common stock. Shares awarded under the plan are fully vested and entitle the stockholder to all rights of common stock ownership except that shares may not be assigned, pledged, hypothecated or otherwise transferred during the restriction period. In general, the restriction period ends at the earliest of (i) ten years from the award date, (ii) the date of the director's death or permanent disability, (iii) five years (or earlier with the approval of the Board of Directors) after the director's date of retirement from the Board of Directors, (iv) the date the director has both retired from the Board of Directors and has reached age 70, or (v) at such other time as determined by the Board of Directors in their sole and absolute discretion. Pursuant to this plan, we issued 44,731 and 35,965 shares related to the years ended December 31, 2024 and 2023, respectively. In addition to the mandatory retainer fee received in restricted stock, directors may elect to receive shares of Class A common stock in lieu of cash for up to 100% of the balance of their annual retainer, committee retainer and any committee chairman's fees. These voluntary shares are not subject to any restrictions. There were no shares issued under voluntary elections in 2024. Total shares issued under voluntary elections were 1,603 in 2023. After the issuance of these shares, there were 53,748 shares of Class A common stock available for issuance under this plan. Compensation expense related to these awards was $1.3 million ($1.0 million net of tax) and $1.3 million ($1.1 million net of tax) for the years ended December 31, 2024 and 2023, respectively. Compensation expense represents fair value based on the market price of the shares of Class A common stock at the grant date.
Financial Instruments	Financial Instruments: Financial instruments held by us include cash and cash equivalents, accounts receivable, equity securities, accounts payable, revolving credit agreements and long-term debt.
Fair Value Measurements	Fair Value Measurements: We account for the fair value measurement of our financial assets and liabilities in accordance with U.S. generally accepted accounting principles, which defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A fair value hierarchy requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. Described below are the three levels of inputs that may be used to measure fair value: Level 1 - Quoted prices in active markets that are accessible at the measurement date for identical assets or liabilities. Level 2 - Observable prices that are based on inputs not quoted on active markets, but corroborated by market data. Level 3 - Unobservable inputs are used when little or no market data is available. The hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The classification of fair value measurements within the hierarchy is based upon the lowest level of input that is significant to the measurement. See Note 9 for further discussion of fair value measurements.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Accounting Standards Adopted in 2024: Effective for the year ended December 31, 2024, we adopted ASU No. 2023-07, Segment Reporting (Topic 280), (ASU 2023-07), which enhances reportable segment disclosure requirements in part by requiring entities to disclose significant expenses related to their reportable segments. ASU 2023-07 also requires disclosure of the title and position of the company’s Chief Operating Decision Maker (CODM) and how the CODM uses financial reporting to assess segment performance and allocate resources. The adoption of this standard only impacts disclosures and did not have a material impact on our Financial Statements. Accounting Standards Not Yet Adopted: In December 2023, the Financial Accounting Standards Board (FASB) issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09), which requires entities to disclose more detailed information about their effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. The adoption of this standard only impacts disclosures and is not expected to have a material impact on our Financial Statements. In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40) (ASU 2024-03), which requires entities to disclose disaggregated information about certain income statement expense line items in the notes to their financial statements on an annual and interim basis. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027, with early adoption permitted. We are currently in the process of evaluating the impact of this ASU on our Financial Statements and related disclosures.
Reclassification	Reclassification: Certain reclassifications have been made to the prior periods’ Consolidated Financial Statements to conform to the current period's presentation.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2024

Use of Estimates: The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and judgments. These estimates and judgments affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities (if any) at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash and Cash Equivalents: Cash and cash equivalents include cash in banks and highly liquid investments with original maturities of three months or less.

Property, Plant and Equipment, Net

Property, Plant and Equipment, Net: Property, plant and equipment are initially recorded at cost. Depreciation, depletion and amortization are provided in amounts sufficient to amortize the cost of the assets, including assets recorded under finance leases, over their estimated useful lives using the straight-line method or the units-of-production method. Buildings and building improvements are depreciated over the life of the asset, which is generally 30 years. Estimated lives for machinery and equipment generally range from three to 15 years. The units-of-production method is used to amortize certain assets based on estimated recoverable tonnages. Repairs and maintenance costs are expensed when incurred, unless such costs extend the estimated useful life of the asset, in which case such costs are capitalized and depreciated. Asset retirement costs associated with asset retirement obligations are capitalized with the carrying amount of the related long-lived asset and depreciated over the asset's estimated useful life.

Royalty Interests in Oil and Natural Gas Properties

Royalty Interests in Oil and Natural Gas Properties: We follow the successful efforts method of accounting for royalty and mineral interests. Under this method, costs to acquire mineral and royalty interests in oil and natural gas properties are capitalized when incurred. Acquisitions of royalty interests of oil and natural gas properties are considered asset acquisitions and are recorded at cost. As an owner of mineral and royalty interests and not working interests, we are not required to make capital expenditures and did not make capital expenditures to convert proved undeveloped reserves from undeveloped to developed.

Acquisition costs of proved royalty and mineral interests are amortized using the units of production method over the life of the property, which is estimated using proved reserves. For purposes of amortization, interests in oil and natural gas properties are grouped in a reasonable aggregation of properties with common geological structural features or stratigraphic condition.

We review and evaluate our royalty interests in oil and natural gas properties for impairment when events or changes in circumstances indicate that the related carrying amounts may not be recoverable. Proved oil and gas properties are reviewed for impairment when events and circumstances indicate a potential decline in the fair value of such properties below the carrying value, such as a downward revision of the reserve estimates or lower commodity prices. When such events or changes in circumstances occur, we estimate the undiscounted future cash flows expected in connection with the properties and compare such future cash flows to the carrying amounts of the properties to determine if the carrying amounts are recoverable. If the carrying value of the properties is determined to not be recoverable based on the undiscounted cash flows, an impairment charge is recognized by comparing the carrying value to the estimated fair value of the properties.

Long-Lived Assets

Long-Lived Assets: We periodically evaluate long-lived assets for impairment when changes in circumstances or the occurrence of certain events indicate the carrying amount of an asset or asset group may not be recoverable. Upon identification of indicators of impairment, we evaluate the carrying value of the asset by comparing the estimated future undiscounted cash flows generated from the use of the asset or asset group and its eventual disposition with the asset's net carrying value. If the carrying value of an asset is considered impaired, an impairment charge is recorded for the amount that the carrying value of the long-lived asset or asset group exceeds its fair value. Fair value is estimated as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

Identifying and assessing whether impairment indicators exist, or if events or changes in circumstances have occurred, including assumptions about future power plant dispatch levels, changes in future sales price, operating costs and other factors that impact anticipated revenue and customer demand, requires significant judgment. We determined that indicators of impairment existed at MLMC during the fourth quarter of 2023 and, as a result, MLMC's long-lived assets were reviewed for impairment. We assessed the recoverability of the MLMC asset group and determined that the assets were not fully recoverable when compared to the remaining future undiscounted cash flows from these assets. As a result, we estimated the fair value of the asset group which resulted in a non-cash, long-lived asset impairment charge of $65.9 million in 2023.

Self-insurance Liabilities

Self-insurance Liabilities: We are generally self-insured for medical claims, certain workers’ compensation claims and certain closed mine liabilities. An estimated provision for claims reported and for claims incurred but not yet reported under the self-insurance programs is recorded and revised periodically based on industry trends, historical experience and management judgment. In addition, industry trends are considered within management's judgment for valuing claims. Changes in assumptions for such matters as legal judgments and settlements, inflation rates, medical costs and actual experience could cause estimates to change in the near term.

Stock Compensation

Stock Compensation: We maintain a long-term incentive program that allow for the grant of shares of Class A common stock, subject to restrictions, as a means of retaining and rewarding selected employees for long-term performance and to increase their ownership in NACCO. Shares awarded under the plans are fully vested and entitle the stockholder to all rights of common stock ownership except that shares may not be assigned, pledged or otherwise transferred during the restriction period. In general, for shares awarded for years ended December 31, 2024 and December 31, 2023, the restriction period ends at the earliest of (i) three years after the participant's retirement date, (ii) three, five or ten years from the award date, or (iii) the participant's death or permanent disability. Pursuant to the plans, we issued 162,670 and 120,649 shares related to the years ended December 31, 2024 and 2023, respectively. After the issuance of these shares, there were 616,681 shares of Class A common stock available for issuance under these plans. Compensation expense related to these share awards was $5.2 million ($4.1 million net of tax) and $4.1 million ($3.3 million net of tax) for the years ended December 31, 2024 and 2023, respectively. Compensation expense represents fair value based on the market price of the shares of Class A common stock at the grant date.

We also have a stock compensation plan for non-employee directors under which a portion of the annual retainer for each non-employee director is paid in restricted shares of Class A common stock. For the year ended December 31, 2024 and 2023, $110,000 ($150,000 for the Chairman) of the non-employee director's annual retainer of $175,000 ($250,000 for the Chairman) was paid in restricted shares of Class A common stock. Shares awarded under the plan are fully vested and entitle the stockholder to all rights of common stock ownership except that shares may not be assigned, pledged, hypothecated or

otherwise transferred during the restriction period. In general, the restriction period ends at the earliest of (i) ten years from the award date, (ii) the date of the director's death or permanent disability, (iii) five years (or earlier with the approval of the Board of Directors) after the director's date of retirement from the Board of Directors, (iv) the date the director has both retired from the Board of Directors and has reached age 70, or (v) at such other time as determined by the Board of Directors in their sole and absolute discretion. Pursuant to this plan, we issued 44,731 and 35,965 shares related to the years ended December 31, 2024 and 2023, respectively. In addition to the mandatory retainer fee received in restricted stock, directors may elect to receive shares of Class A common stock in lieu of cash for up to 100% of the balance of their annual retainer, committee retainer and any committee chairman's fees. These voluntary shares are not subject to any restrictions. There were no shares issued under voluntary elections in 2024. Total shares issued under voluntary elections were 1,603 in 2023. After the issuance of these shares, there were 53,748 shares of Class A common stock available for issuance under this plan. Compensation expense related to these awards was $1.3 million ($1.0 million net of tax) and $1.3 million ($1.1 million net of tax) for the years ended December 31, 2024 and 2023, respectively. Compensation expense represents fair value based on the market price of the shares of Class A common stock at the grant date.

Financial Instruments

Financial Instruments: Financial instruments held by us include cash and cash equivalents, accounts receivable, equity securities, accounts payable, revolving credit agreements and long-term debt.

Fair Value Measurements

Fair Value Measurements: We account for the fair value measurement of our financial assets and liabilities in accordance with U.S. generally accepted accounting principles, which defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

A fair value hierarchy requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value.

Described below are the three levels of inputs that may be used to measure fair value:

Level 1 - Quoted prices in active markets that are accessible at the measurement date for identical assets or liabilities.

Level 2 - Observable prices that are based on inputs not quoted on active markets, but corroborated by market data.

Level 3 - Unobservable inputs are used when little or no market data is available.

The hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The classification of fair value measurements within the hierarchy is based upon the lowest level of input that is significant to the measurement. See Note 9 for further discussion of fair value measurements.

Recently Issued Accounting Standards

Accounting Standards Adopted in 2024: Effective for the year ended December 31, 2024, we adopted ASU No. 2023-07, Segment Reporting (Topic 280), (ASU 2023-07), which enhances reportable segment disclosure requirements in part by requiring entities to disclose significant expenses related to their reportable segments. ASU 2023-07 also requires disclosure of the title and position of the company’s Chief Operating Decision Maker (CODM) and how the CODM uses financial reporting to assess segment performance and allocate resources. The adoption of this standard only impacts disclosures and did not have a material impact on our Financial Statements.

Accounting Standards Not Yet Adopted: In December 2023, the Financial Accounting Standards Board (FASB) issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09), which requires entities to disclose more detailed information about their effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. The adoption of this standard only impacts disclosures and is not expected to have a material impact on our Financial Statements.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40) (ASU 2024-03), which requires entities to disclose disaggregated information about certain income statement expense line items in the notes to their financial statements on an annual and interim basis. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027, with early adoption permitted. We are currently in the process of evaluating the impact of this ASU on our Financial Statements and related disclosures.

Reclassification

Reclassification: Certain reclassifications have been made to the prior periods’ Consolidated Financial Statements to conform to the current period's presentation.