Principles of Consolidation and Nature of Operations	12 Months Ended
Dec. 31, 2019
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.^® (the parent company or “NACCO”) and its wholly owned subsidiaries (“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"). In the first quarter of 2019, the Company changed its segment reporting to 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. Prior to January 1, 2019, NACoal was the Company’s operating segment. NACCO and Other, which included parent company operations and Bellaire Corporation (“Bellaire”), was the Company’s non-operating segment. Historical financial information for 2018 has been recast to conform to the current presentation. 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 The operating coal mines are: Bisti Fuels 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”). Liberty Fuels Company, LLC (“Liberty”) ceased all mining and delivery of lignite in 2017. The terms of the contract specified that Mississippi Power was responsible for all mine closure costs and Liberty receives compensation for providing mine reclamation services. As of December 31, 2019, the mine areas have been reclaimed and final mine reclamation activities, primarily monitoring, will continue until final bond release. 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. All of the Unconsolidated Subsidiaries are accounted for under the equity method. See Note 17 for further discussion. 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. Centennial Natural Resources (“Centennial”), located in Alabama, ceased coal production at the end of 2015. Since 2015, the Company has sold or transferred certain Centennial equipment and mineral reserves. The Company continues to evaluate strategies for the remaining mineral reserves and a dragline, which have no remaining book value. Cash expenditures related to mine reclamation at Centennial will continue until mine reclamation is complete, or ownership of, or responsibility for, the remaining mines is transferred. Centennial is a consolidated entity within the Coal Mining segment as the Company is responsible for carrying costs and final mine reclamation. 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 to serve as exclusive contract miner for the Thacker Pass lithium project in northern Nevada. NAMining utilizes both fixed price and cost plus a management fee contract structures. Certain of the entities within 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 promotes the development of the Company’s oil, gas 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.

Principles of Consolidation and Nature of Operations

The Consolidated Financial Statements include the accounts of NACCO Industries, Inc.^® (the parent company or “NACCO”) and its wholly owned subsidiaries (“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"). In the first quarter of 2019, the Company changed its segment reporting to 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. Prior to January 1, 2019, NACoal was the Company’s operating segment. NACCO and Other, which included parent company operations and Bellaire Corporation (“Bellaire”), was the Company’s non-operating segment. Historical financial information for 2018 has been recast to conform to the current presentation. 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

The operating coal mines are: Bisti Fuels 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”). Liberty Fuels Company, LLC (“Liberty”) ceased all mining and delivery of lignite in 2017. The terms of the contract specified that Mississippi Power was responsible for all mine closure costs and Liberty receives compensation for providing mine reclamation services. As of December 31, 2019, the mine areas have been reclaimed and final mine reclamation activities, primarily monitoring, will continue until final bond release.

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. All of the Unconsolidated Subsidiaries are accounted for under the equity method. See Note 17 for further discussion.

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.

Centennial Natural Resources (“Centennial”), located in Alabama, ceased coal production at the end of 2015. Since 2015, the Company has sold or transferred certain Centennial equipment and mineral reserves. The Company continues to evaluate strategies for the remaining mineral reserves and a dragline, which have no remaining book value. Cash expenditures related to mine reclamation at Centennial will continue until mine reclamation is complete, or ownership of, or responsibility for, the remaining mines is transferred. Centennial is a consolidated entity within the Coal Mining segment as the Company is responsible for carrying costs and final mine reclamation.

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 to serve as exclusive contract miner for the Thacker Pass lithium project in northern Nevada. NAMining utilizes both fixed price and cost plus a management fee contract structures. Certain of the entities within 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 promotes the development of the Company’s oil, gas 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.