Proven and Probable Coal Reserves

No definition available.

Name:	nacco_CoalMiningReservesProvedAndProbableReservesQuantity
Namespace Prefix:	nacco_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	instant

- Definition

Depreciation, Depletion and Amortization, Production

+ References

No definition available.

+ Details

Name:	nacco_DepreciationDepletionAndAmortizationProduction
Namespace Prefix:	nacco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.14)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 14

-Article 5

+ Details

Name:	us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228

+ Details

Name:	us-gaap_AssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 8

-Article 7

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230

+ Details

Name:	us-gaap_TangibleAssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=nacco_CoalLandsAndRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=nacco_PlantAndEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=nacco_ReedMineralsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nacco_HbbMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nacco_KcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nacco_NaccoAndOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nacco_NacoalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Property, Plant and Equipment, Net (Details) (USD $)	12 Months Ended			3 Months Ended
Property, Plant and Equipment, Net (Details) (USD $)	Dec. 31, 2014 T	Dec. 31, 2013 T	Dec. 31, 2012	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 282,303,000us-gaap_PropertyPlantAndEquipmentGross	$ 342,688,000us-gaap_PropertyPlantAndEquipmentGross		$ 282,303,000us-gaap_PropertyPlantAndEquipmentGross
Less allowances for depreciation, depletion and amortization	122,659,000	123,432,000		122,659,000
Property, plant and equipment, net	159,644,000us-gaap_PropertyPlantAndEquipmentNet	219,256,000us-gaap_PropertyPlantAndEquipmentNet		159,644,000us-gaap_PropertyPlantAndEquipmentNet
Depreciation, depletion and amortization	24,800,000	20,900,000	15,200,000
Proved and probable reserves (tons)	1,000,000,000	1,200,000,000		1,000,000,000
Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	54,923,000	83,962,000		54,923,000
Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	227,380,000	258,726,000		227,380,000
NACoal \| Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	54,228,000	83,736,000		54,228,000
NACoal \| Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	146,994,000	180,418,000		146,994,000
HBB \| Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	226,000	226,000		226,000
HBB \| Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	49,579,000	45,141,000		49,579,000
NACCO and Other \| Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	469,000	0		469,000
NACCO and Other \| Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	4,655,000	4,552,000		4,655,000
KC
Property, Plant and Equipment [Line Items]
Tangible asset impairment charges	900,000	1,100,000	700,000
KC \| Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	26,152,000	28,615,000		26,152,000
Reed Minerals \| NACoal
Property, Plant and Equipment [Line Items]
Reed Minerals long-lived asset impairment charge				105,100,000
Reed Minerals \| NACoal \| Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	7,200,000			7,200,000
Reed Minerals \| NACoal \| Plant and Equipment
Property, Plant and Equipment [Line Items]
Reed Minerals long-lived asset impairment charge				$ 99,400,000