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Business Segments (Textual) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Segment Reporting Information [Line Items]      
Management fees expense $ 8.5us-gaap_ManagementFeeExpense $ 6.8us-gaap_ManagementFeeExpense $ 6.9us-gaap_ManagementFeeExpense
Hyster-Yale      
Segment Reporting Information [Line Items]      
Management fees expense     $ 9.6us-gaap_ManagementFeeExpense
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= nacco_HysterYaleMember
Customer concentration risk | Sales revenue, net | Choctaw Generation Limited Partnership | NACoal      
Segment Reporting Information [Line Items]      
Revenue from major customer, percentage 39.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_NacoalMember
/ us-gaap_MajorCustomersAxis
= nacco_ChoctawGenerationLimitedPartnershipMember		 42.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_NacoalMember
/ us-gaap_MajorCustomersAxis
= nacco_ChoctawGenerationLimitedPartnershipMember		 56.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_NacoalMember
/ us-gaap_MajorCustomersAxis
= nacco_ChoctawGenerationLimitedPartnershipMember
Customer concentration risk | Sales revenue, net | Alabama Coal Cooperative | Reed Minerals      
Segment Reporting Information [Line Items]      
Revenue from major customer, percentage 27.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_ReedMineralsMember
/ us-gaap_MajorCustomersAxis
= nacco_AlabamaCoalCooperativeMember		 27.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_ReedMineralsMember
/ us-gaap_MajorCustomersAxis
= nacco_AlabamaCoalCooperativeMember		 15.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_ReedMineralsMember
/ us-gaap_MajorCustomersAxis
= nacco_AlabamaCoalCooperativeMember
Customer concentration risk | Sales revenue, net | Wal-Mart | HBB      
Segment Reporting Information [Line Items]      
Revenue from major customer, percentage 33.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_HbbMember
/ us-gaap_MajorCustomersAxis
= nacco_WalMartMember		 31.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_HbbMember
/ us-gaap_MajorCustomersAxis
= nacco_WalMartMember		 31.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_HbbMember
/ us-gaap_MajorCustomersAxis
= nacco_WalMartMember
Customer concentration risk | Sales revenue, net | Five Largest Customers | HBB      
Segment Reporting Information [Line Items]      
Revenue from major customer, percentage 56.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_HbbMember
/ us-gaap_MajorCustomersAxis
= nacco_FiveLargestCustomersMember		 55.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_HbbMember
/ us-gaap_MajorCustomersAxis
= nacco_FiveLargestCustomersMember		 53.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ dei_LegalEntityAxis
= nacco_HbbMember
/ us-gaap_MajorCustomersAxis
= nacco_FiveLargestCustomersMember