Nature of Operations and Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	The accompanying Unaudited Condensed Consolidated Financial Statements include the accounts of NACCO Industries, Inc.® (“NACCO”) and its wholly owned subsidiaries (collectively, “NACCO Industries, Inc. and Subsidiaries” or the “Company”). Intercompany accounts and transactions are eliminated in consolidation. NACCO is the public holding company for The North American Coal Corporation® ("NACoal"). The Company has three operating segments: Coal Mining, North American Mining (“NAMining”) and Minerals Management. The Company also has unallocated items not directly attributable to a reportable segment. See Note 9 to the Unaudited Condensed Consolidated Financial Statements for further discussion of segment reporting. The Company’s operating segments are further described below: Coal Mining Segment During the nine months ended September 30, 2020, the operating coal mines were: Bisti Fuels LLC (“Bisti”), Caddo Creek Resources Company, LLC (“Caddo Creek”), The Coteau Properties Company (“Coteau”), Coyote Creek Mining Company, LLC (“Coyote Creek”), Demery Resources Company, LLC (“Demery”), The Falkirk Mining Company (“Falkirk”), Mississippi Lignite Mining Company (“MLMC”) and The Sabine Mining Company (“Sabine”). On September 30, 2020, Caddo Creek’s customer, a division of Cabot Corporation, entered into a long-term supply agreement with a subsidiary of Advanced Emissions Solutions (“AES”) as well as an agreement for the sale of the Marshall Mine, operated by Caddo Creek, to a subsidiary of AES. AES announced its intent to close the Marshall Mine. Caddo Creek entered into a contract with a subsidiary of AES to perform the required mine reclamation. In 2019, total tons delivered by the Coal Mining segment was 34.6 million tons, of which 0.2 million tons related to Caddo Creek. All production from the Sabine Mine is delivered to Southwestern Electric Power Company's Henry W. Pirkey Plant. The Pirkey power plant has been dispatched at a lower rate during the first nine months of 2020 compared with the first nine months of 2019, resulting in a 43% reduction in tons delivered in 2020 compared with 2019. During the third quarter of 2020, Sabine’s customer reduced its expected future annual deliveries to be between 1.4 million and 1.7 million tons of lignite coal. Sabine historically has delivered between 2.5 million and 3.5 million tons of lignite coal annually, including 2.6 million tons in 2019 and 3.8 million tons in 2018. The contract mining agreement between Camino Real Fuels, LLC (“Camino Real”) and its customer, Dos Republicas Coal Partnership (“DRCP”), terminated effective July 1, 2020 as a result of the unexpected termination by Comisión Federal de Electricidad (“CFE”) of its coal supply contract with an affiliate of DRCP. The termination of the contract between CFE and DRCP eliminated DRCP’s need for coal from Camino Real's Eagle Pass Mine, and resulted in mine closure. Mine reclamation is the responsibility of DRCP. Camino Real has no legal obligation to perform mine reclamation. The Company received certain inventory as well as a securitized note in settlement of the outstanding receivable balance due from DRCP. During the fourth quarter of 2020, the Company received payment for the outstanding balance on the securitized note, which was $2.3 million as of September 30, 2020, and is included within Other current assets on the Unaudited Condensed Consolidated Balance Sheet. At all operating coal mines other than MLMC, the Company is paid a management fee per ton of coal or heating unit (MMBtu) delivered. Each contract specifies the indices and mechanics by which fees change over time, generally in line with broad measures of U.S. inflation. The customers are responsible for funding all mine operating costs, including final mine reclamation, and directly or indirectly providing all of the capital required to build and operate the mine. This contract structure eliminates exposure to spot coal market price fluctuations while providing steady income and cash flow with minimal capital investment. Other than at Coyote Creek, debt financing provided by or supported by the customers is without recourse to NACCO and NACoal. See Note 7 for further discussion of Coyote Creek's guarantees. All operating coal mines other than MLMC meet the definition of a variable interest entity (“VIE”). In each case, NACCO is not the primary beneficiary of the VIE as it does not exercise financial control; therefore, NACCO does not consolidate the results of these operations within its financial statements. Instead, these contracts are accounted for as equity method investments. The income before income taxes associated with these VIE's is reported as Earnings of unconsolidated operations on the Consolidated Statements of Operations and the Company’s investment is reported on the line Investments in unconsolidated subsidiaries in the Consolidated Balance Sheets. The mines that meet the definition of a VIE are referred to collectively as the “Unconsolidated Subsidiaries.” For tax purposes, the Unconsolidated Subsidiaries are included within the NACCO consolidated U.S. tax return; therefore, the income tax expense line on the Consolidated Statements of Operations includes income taxes related to these entities. All of the Unconsolidated Subsidiaries are accounted for under the equity method. See Note 7 for further discussion. Camino Real and Caddo Creek previously met the definition of a variable interest entity of which the Company was not the primary beneficiary and therefore NACCO did not consolidate the results of operations within its financial statements. As a result of the events described above, Camino Real and Caddo Creek are no longer VIEs. Camino Real’s financial position was consolidated within NACCO’s financial statements beginning on June 30, 2020. Camino Real’s results of operations for the three months ended September 30, 2020 did not materially change the Company's Unaudited Condensed Consolidated Statements of Operations. Caddo Creek’s financial position will be consolidated within NACCO’s financial statements beginning in the fourth quarter of 2020. The consolidation of these entities will not materially change the Company’s Unaudited Condensed Consolidated Balance Sheet. The MLMC contract is the only operating coal contract in which the Company is responsible for all operating costs, capital requirements and final mine reclamation; therefore, MLMC is consolidated within NACCO’s financial statements. MLMC sells coal to its customer at a contractually agreed-upon price which adjusts monthly, primarily based on changes in the level of established indices which reflect general U.S. inflation rates. As of September 30, 2020, all of the Liberty Fuels Company, LLC mine areas have been reclaimed and final mine reclamation activities, primarily monitoring, will continue until final bond release. Centennial Natural Resources (“Centennial”), located in Alabama, ceased coal production at the end of 2015. NAMining Segment The NAMining segment provides value-added contract mining and other services for producers of aggregates, lithium and other minerals. The segment is a primary platform for the Company’s growth and diversification outside of the coal industry. NAMining provides contract mining services for independently owned mines and quarries, creating value for its customers by performing the mining aspects of its customers’ operations. This allows customers to focus on their areas of expertise: materials handling and processing, product sales and distribution. NAMining operates primarily at limestone quarries in Florida, but is focused on expanding outside of Florida and into mining materials other than limestone. During 2019, the Company entered into a mining agreement, through a new subsidiary, Sawtooth Mining, to serve as exclusive contract miner for the Thacker Pass lithium project in northern Nevada. The Thacker Pass Project is 100% owned by Lithium Nevada Corp. Sawtooth Mining will provide comprehensive mining services and certain equipment during the 20-year contract term. During the development of the project, Sawtooth Mining will provide Lithium Nevada $3.5 million in cash to assist in project development, of which $3.0 million and $1.5 million has been provided as of September 30, 2020 and December 31, 2019, respectively, and included within Other non-current assets on the Unaudited Condensed Consolidated Balance Sheets. Lithium Nevada is in the process of securing permits and currently expects to commence construction in 2021 and production of lithium products in 2023. NAMining utilizes both fixed price and cost plus management fee contract structures. Certain of the entities within the NAMining segment are VIEs and are accounted for under the equity method as Unconsolidated Subsidiaries. See Note 7 for further discussion. Minerals Management Segment The Minerals Management segment promotes the development of the Company’s gas, oil and coal reserves, generating income primarily from royalty-based lease payments from third parties. The Company’s gas, oil and undeveloped coal reserves are located in Ohio (Utica and Marcellus shale natural gas), Louisiana (Haynesville shale and Cotton Valley formation natural gas), Mississippi (coal), Pennsylvania (coal, coalbed methane and Marcellus shale natural gas), Alabama (coal and coalbed methane and natural gas) and North Dakota (coal). The majority of the Company’s existing reserves were acquired as part of its historical coal mining operations. The Minerals Management segment derives income primarily by entering into contracts with third-party operators, granting them the rights to explore, produce and sell natural resources in exchange for royalty payments based on the lessees' sales of natural gas and, to a lesser extent, oil and coal. Specialized employees in the Minerals Management segment also provide surface and mineral acquisition and lease maintenance services related to Company operations.
Basis of Presentation	Basis of Presentation: These financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the financial position of the Company at September 30, 2020, the results of its operations, comprehensive income, cash flows and changes in equity for the nine months ended September 30, 2020 and 2019 have been included. These Unaudited Condensed Consolidated Financial Statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2019. The balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all of the information or notes required by U.S. GAAP for complete financial statements. Certain amounts in prior period Unaudited Condensed Consolidated Financial Statements have been reclassified to conform to the current period's presentation.

The accompanying Unaudited Condensed Consolidated Financial Statements include the accounts of NACCO Industries, Inc.® (“NACCO”) and its wholly owned subsidiaries (collectively, “NACCO Industries, Inc. and Subsidiaries” or the “Company”). Intercompany accounts and transactions are eliminated in consolidation. NACCO is the public holding company for The North American Coal Corporation® ("NACoal"). The Company has three operating segments: Coal Mining, North American Mining (“NAMining”) and Minerals Management. The Company also has unallocated items not directly attributable to a reportable segment. See Note 9 to the Unaudited Condensed Consolidated Financial Statements for further discussion of segment reporting.

During the nine months ended September 30, 2020, the operating coal mines were: Bisti Fuels LLC (“Bisti”), Caddo Creek Resources Company, LLC (“Caddo Creek”), The Coteau Properties Company (“Coteau”), Coyote Creek Mining Company, LLC (“Coyote Creek”), Demery Resources Company, LLC (“Demery”), The Falkirk Mining Company (“Falkirk”), Mississippi Lignite Mining Company (“MLMC”) and The Sabine Mining Company (“Sabine”).

On September 30, 2020, Caddo Creek’s customer, a division of Cabot Corporation, entered into a long-term supply agreement with a subsidiary of Advanced Emissions Solutions (“AES”) as well as an agreement for the sale of the Marshall Mine, operated by Caddo Creek, to a subsidiary of AES. AES announced its intent to close the Marshall Mine. Caddo Creek entered into a contract with a subsidiary of AES to perform the required mine reclamation. In 2019, total tons delivered by the Coal Mining segment was 34.6 million tons, of which 0.2 million tons related to Caddo Creek.

All production from the Sabine Mine is delivered to Southwestern Electric Power Company's Henry W. Pirkey Plant. The Pirkey power plant has been dispatched at a lower rate during the first nine months of 2020 compared with the first nine months of 2019, resulting in a 43% reduction in tons delivered in 2020 compared with 2019. During the third quarter of 2020, Sabine’s customer reduced its expected future annual deliveries to be between 1.4 million and 1.7 million tons of lignite coal. Sabine historically has delivered between 2.5 million and 3.5 million tons of lignite coal annually, including 2.6 million tons in 2019 and 3.8 million tons in 2018.

The contract mining agreement between Camino Real Fuels, LLC (“Camino Real”) and its customer, Dos Republicas Coal Partnership (“DRCP”), terminated effective July 1, 2020 as a result of the unexpected termination by Comisión Federal de Electricidad (“CFE”) of its coal supply contract with an affiliate of DRCP. The termination of the contract between CFE and DRCP eliminated DRCP’s need for coal from Camino Real's Eagle Pass Mine, and resulted in mine closure. Mine reclamation is the responsibility of DRCP. Camino Real has no legal obligation to perform mine reclamation. The Company received certain inventory as well as a securitized note in settlement of the outstanding receivable balance due from DRCP. During the fourth quarter of 2020, the Company received payment for the outstanding balance on the securitized note, which was $2.3 million as of September 30, 2020, and is included within Other current assets on the Unaudited Condensed Consolidated Balance Sheet.

At all operating coal mines other than MLMC, the Company is paid a management fee per ton of coal or heating unit (MMBtu) delivered. Each contract specifies the indices and mechanics by which fees change over time, generally in line with broad measures of U.S. inflation. The customers are responsible for funding all mine operating costs, including final mine reclamation, and directly or indirectly providing all of the capital required to build and operate the mine. This contract structure eliminates exposure to spot coal market price fluctuations while providing steady income and cash flow with minimal capital investment. Other than at Coyote Creek, debt financing provided by or supported by the customers is without recourse to NACCO and NACoal. See Note 7 for further discussion of Coyote Creek's guarantees.

All operating coal mines other than MLMC meet the definition of a variable interest entity (“VIE”). In each case, NACCO is not the primary beneficiary of the VIE as it does not exercise financial control; therefore, NACCO does not consolidate the results of these operations within its financial statements. Instead, these contracts are accounted for as equity method investments. The income before income taxes associated with these VIE's is reported as Earnings of unconsolidated operations on the Consolidated Statements of Operations and the Company’s investment is reported on the line Investments in

unconsolidated subsidiaries in the Consolidated Balance Sheets. The mines that meet the definition of a VIE are referred to collectively as the “Unconsolidated Subsidiaries.” For tax purposes, the Unconsolidated Subsidiaries are included within the NACCO consolidated U.S. tax return; therefore, the income tax expense line on the Consolidated Statements of Operations includes income taxes related to these entities. All of the Unconsolidated Subsidiaries are accounted for under the equity method. See Note 7 for further discussion.

Camino Real and Caddo Creek previously met the definition of a variable interest entity of which the Company was not the primary beneficiary and therefore NACCO did not consolidate the results of operations within its financial statements. As a result of the events described above, Camino Real and Caddo Creek are no longer VIEs. Camino Real’s financial position was consolidated within NACCO’s financial statements beginning on June 30, 2020. Camino Real’s results of operations for the three months ended September 30, 2020 did not materially change the Company's Unaudited Condensed Consolidated Statements of Operations. Caddo Creek’s financial position will be consolidated within NACCO’s financial statements beginning in the fourth quarter of 2020. The consolidation of these entities will not materially change the Company’s Unaudited Condensed Consolidated Balance Sheet.

The MLMC contract is the only operating coal contract in which the Company is responsible for all operating costs, capital requirements and final mine reclamation; therefore, MLMC is consolidated within NACCO’s financial statements. MLMC sells coal to its customer at a contractually agreed-upon price which adjusts monthly, primarily based on changes in the level of established indices which reflect general U.S. inflation rates.

The NAMining segment provides value-added contract mining and other services for producers of aggregates, lithium and other minerals. The segment is a primary platform for the Company’s growth and diversification outside of the coal industry. NAMining provides contract mining services for independently owned mines and quarries, creating value for its customers by performing the mining aspects of its customers’ operations. This allows customers to focus on their areas of expertise: materials handling and processing, product sales and distribution. NAMining operates primarily at limestone quarries in Florida, but is focused on expanding outside of Florida and into mining materials other than limestone.

During 2019, the Company entered into a mining agreement, through a new subsidiary, Sawtooth Mining, to serve as exclusive contract miner for the Thacker Pass lithium project in northern Nevada. The Thacker Pass Project is 100% owned by Lithium Nevada Corp. Sawtooth Mining will provide comprehensive mining services and certain equipment during the 20-year contract term. During the development of the project, Sawtooth Mining will provide Lithium Nevada $3.5 million in cash to assist in project development, of which $3.0 million and $1.5 million has been provided as of September 30, 2020 and December 31, 2019, respectively, and included within Other non-current assets on the Unaudited Condensed Consolidated Balance Sheets. Lithium Nevada is in the process of securing permits and currently expects to commence construction in 2021 and production of lithium products in 2023.

NAMining utilizes both fixed price and cost plus management fee contract structures. Certain of the entities within the NAMining segment are VIEs and are accounted for under the equity method as Unconsolidated Subsidiaries. See Note 7 for further discussion.

The Minerals Management segment promotes the development of the Company’s gas, oil and coal reserves, generating income primarily from royalty-based lease payments from third parties. The Company’s gas, oil and undeveloped coal reserves are located in Ohio (Utica and Marcellus shale natural gas), Louisiana (Haynesville shale and Cotton Valley formation natural gas), Mississippi (coal), Pennsylvania (coal, coalbed methane and Marcellus shale natural gas), Alabama (coal and coalbed methane and natural gas) and North Dakota (coal).

The majority of the Company’s existing reserves were acquired as part of its historical coal mining operations. The Minerals Management segment derives income primarily by entering into contracts with third-party operators, granting them the rights to explore, produce and sell natural resources in exchange for royalty payments based on the lessees' sales of natural gas and, to a lesser extent, oil and coal. Specialized employees in the Minerals Management segment also provide surface and mineral acquisition and lease maintenance services related to Company operations.