Principles of Consolidation and Nature of Operations	12 Months Ended
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation and Nature of Operations	Principles of Consolidation and Nature of Operations The Consolidated Financial Statements include the accounts of NACCO Industries, Inc.® (“NACCO” or the "Company"). NACCO, through a portfolio of mining and natural resources businesses, operates under three business segments: Coal Mining, North American Mining ("NAMining") and Minerals Management. The Coal Mining segment operates surface coal mines under long-term contracts with power generation companies and an activated carbon producer pursuant to a service-based business model. The NAMining segment provides value-added contract mining and other services for producers of aggregates, lithium and other minerals. The Minerals Management segment acquires and promotes the development of oil, gas and coal mineral interests, generating income primarily from royalty-based lease payments from third parties. In addition, the Company has a business providing stream and wetland mitigation solutions. The Company also has unallocated items not directly attributable to a reportable segment. Intercompany accounts and transactions are eliminated in consolidation. See Note 15 to the Consolidated Financial Statements for further discussion of segment reporting. The Company’s operating segments are further described below: Coal Mining Segment During 2020, the Company's operating coal mines were: Bisti Fuels Company, LLC (“Bisti”), Caddo Creek Resources Company, LLC (“Caddo Creek”), Camino Real Fuels, LLC (“Camino Real”), 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”). The Company operates these mines as the North American Coal Corporation® ("NACoal"). Sabine operates the Sabine Mine in Texas. All production from Sabine is delivered to Southwestern Electric Power Company's (“SWEPCO”) Henry W. Pirkey Plant (the “Pirkey Plant”). SWEPCO is an American Electric Power (“AEP”) company. On November 5, 2020, AEP announced it intends to retire the Pirkey Plant in 2023 in order to comply with the U.S. Environmental Protection Agency’s Coal Combustion Residuals rule. The Sabine Mine delivered 1.9 million and 2.6 million tons to the Pirkey Plant in 2020 and 2019, respectively. During 2020, SWEPCO reduced its expected future annual delivery requirements to be between 1.4 million and 1.7 million tons. The Sabine Mine contributed $3.9 million and $4.6 million to Earnings from Unconsolidated Operations during 2020 and 2019, respectively. Coteau operates the Freedom Mine in North Dakota. All coal production from the Freedom Mine is delivered to Basin Electric Power Cooperative (“Basin Electric”). Basin Electric utilizes the coal at the Great Plains Synfuels Plant (the “Synfuels Plant”), Antelope Valley Station and Leland Olds Station. The Synfuels Plant is a coal gasification plant that manufactures synthetic natural gas and produces fertilizers, solvents, phenol, carbon dioxide, and other chemical products for sale. On November 5, 2020, Basin Electric informed its employees and Coteau that it is considering changes that may result in modifications to its Synfuels Plant that could potentially reduce or eliminate coal requirements at the Synfuels Plant beginning in 2026. Basin Electric indicated that if it decides to proceed with any changes that could reduce or eliminate the use of coal, the feedstock change is not expected to occur before 2026. As a result, coal deliveries to the Synfuels Plant are expected to continue until at least 2026. 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. The Marshall Mine delivered 0.1 million and 0.2 million tons during 2020 and 2019, respectively. The contract mining agreement between 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 Eagle Pass Mine delivered 0.3 million and 1.6 million tons during 2020 and 2019, respectively. On May 7, 2020, Great River Energy ("GRE"), Falkirk's customer, announced its intent to retire the Coal Creek Station power plant in the second half of 2022 and modify the Spiritwood Station power plant to be fueled by natural gas. As noted in the announcement, GRE is willing to consider opportunities to sell Coal Creek Station. Falkirk Mine is the sole supplier of lignite coal to Coal Creek Station pursuant to a long-term contract under which Falkirk also supplies approximately 0.3 million tons of lignite coal per year to Spiritwood Station. Falkirk delivered a total of 7.2 million and 7.4 million tons of lignite coal and contributed $16.1 million and $15.9 million to Earnings from Unconsolidated Operations during 2020 and 2019, respectively. 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 provide 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 17 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. See Note 17 for further information on the Unconsolidated Subsidiaries. Camino Real and Caddo Creek previously met the definition of a VIE 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 and Caddo Creek's financial positions were consolidated within NACCO’s financial statements during the second quarter of 2020 and the fourth quarter of 2020, respectively. During 2020, the consolidation of these entities did not materially change the Company’s Consolidated Statements of Operations and 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. 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 of mining activities 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. In addition, NAMining will serve as exclusive contract miner for the Thacker Pass lithium project in northern Nevada. NAMining utilizes both fixed price and 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 17 for further discussion. Minerals Management Segment The Minerals Management segment derives income primarily by leasing its royalty and mineral interests to third-party exploration and production companies, and, to a lesser extent, other mining companies, granting them the rights to explore, develop, mine, produce, market and sell gas, oil, and coal in exchange for royalty payments based on the lessees' sales of those minerals. During 2020, the Minerals Management segment acquired mineral interests in the Permian Basin in Texas and intends to make future acquisitions of mineral and royalty interests that meet the Company’s acquisition criteria as part of its growth strategy. The Company’s legacy royalty and mineral interests 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 legacy reserves were acquired as part of its historical coal mining operations. Specialized employees in the Minerals Management segment also provide surface and mineral acquisition and lease maintenance services related to Company operations.

The Consolidated Financial Statements include the accounts of NACCO Industries, Inc.® (“NACCO” or the "Company"). NACCO, through a portfolio of mining and natural resources businesses, operates under three business segments: Coal Mining, North American Mining ("NAMining") and Minerals Management. The Coal Mining segment operates surface coal mines under long-term contracts with power generation companies and an activated carbon producer pursuant to a service-based business model. The NAMining segment provides value-added contract mining and other services for producers of aggregates, lithium and other minerals. The Minerals Management segment acquires and promotes the development of oil, gas and coal mineral interests, generating income primarily from royalty-based lease payments from third parties. In addition, the Company has a business providing stream and wetland mitigation solutions.

The Company also has unallocated items not directly attributable to a reportable segment. Intercompany accounts and transactions are eliminated in consolidation. See Note 15 to the Consolidated Financial Statements for further discussion of segment reporting.

During 2020, the Company's operating coal mines were: Bisti Fuels Company, LLC (“Bisti”), Caddo Creek Resources Company, LLC (“Caddo Creek”), Camino Real Fuels, LLC (“Camino Real”), 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”). The Company operates these mines as the North American Coal Corporation® ("NACoal").

Sabine operates the Sabine Mine in Texas. All production from Sabine is delivered to Southwestern Electric Power Company's (“SWEPCO”) Henry W. Pirkey Plant (the “Pirkey Plant”). SWEPCO is an American Electric Power (“AEP”) company. On November 5, 2020, AEP announced it intends to retire the Pirkey Plant in 2023 in order to comply with the U.S. Environmental Protection Agency’s Coal Combustion Residuals rule. The Sabine Mine delivered 1.9 million and 2.6 million tons to the Pirkey Plant in 2020 and 2019, respectively. During 2020, SWEPCO reduced its expected future annual delivery requirements to be between 1.4 million and 1.7 million tons. The Sabine Mine contributed $3.9 million and $4.6 million to Earnings from Unconsolidated Operations during 2020 and 2019, respectively.

Coteau operates the Freedom Mine in North Dakota. All coal production from the Freedom Mine is delivered to Basin Electric Power Cooperative (“Basin Electric”). Basin Electric utilizes the coal at the Great Plains Synfuels Plant (the “Synfuels Plant”), Antelope Valley Station and Leland Olds Station. The Synfuels Plant is a coal gasification plant that manufactures synthetic natural gas and produces fertilizers, solvents, phenol, carbon dioxide, and other chemical products for sale. On November 5, 2020, Basin Electric informed its employees and Coteau that it is considering changes that may result in modifications to its Synfuels Plant that could potentially reduce or eliminate coal requirements at the Synfuels Plant beginning in 2026. Basin Electric indicated that if it decides to proceed with any changes that could reduce or eliminate the use of coal, the feedstock change is not expected to occur before 2026. As a result, coal deliveries to the Synfuels Plant are expected to continue until at least 2026.

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. The Marshall Mine delivered 0.1 million and 0.2 million tons during 2020 and 2019, respectively.

The contract mining agreement between 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 Eagle Pass Mine delivered 0.3 million and 1.6 million tons during 2020 and 2019, respectively.

On May 7, 2020, Great River Energy ("GRE"), Falkirk's customer, announced its intent to retire the Coal Creek Station power plant in the second half of 2022 and modify the Spiritwood Station power plant to be fueled by natural gas. As noted in the announcement, GRE is willing to consider opportunities to sell Coal Creek Station. Falkirk Mine is the sole supplier of lignite coal to Coal Creek Station pursuant to a long-term contract under which Falkirk also supplies approximately 0.3 million tons of lignite coal per year to Spiritwood Station. Falkirk delivered a total of 7.2 million and 7.4 million tons of lignite coal and contributed $16.1 million and $15.9 million to Earnings from Unconsolidated Operations during 2020 and 2019, respectively.

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 provide 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 17 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. See Note 17 for further information on the Unconsolidated Subsidiaries.

Camino Real and Caddo Creek previously met the definition of a VIE 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 and Caddo Creek's financial positions were consolidated within NACCO’s financial statements during the second quarter of 2020 and the fourth quarter of 2020, respectively. During 2020, the consolidation of these entities did not materially change the Company’s Consolidated Statements of Operations and 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 of mining activities 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. In addition, NAMining will serve as exclusive contract miner for the Thacker Pass lithium project in northern Nevada.

NAMining utilizes both fixed price and 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 17 for further discussion.

The Minerals Management segment derives income primarily by leasing its royalty and mineral interests to third-party exploration and production companies, and, to a lesser extent, other mining companies, granting them the rights to explore, develop, mine, produce, market and sell gas, oil, and coal in exchange for royalty payments based on the lessees' sales of those minerals. During 2020, the Minerals Management segment acquired mineral interests in the Permian Basin in Texas and intends to make future acquisitions of mineral and royalty interests that meet the Company’s acquisition criteria as part of its growth strategy.

The Company’s legacy royalty and mineral interests 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 legacy reserves were acquired as part of its historical coal mining operations. Specialized employees in the Minerals Management segment also provide surface and mineral acquisition and lease maintenance services related to Company operations.