Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 207,721	$ 195,552
Less allowances for depreciation, depletion and amortization	87,653	80,446
Property, plant and equipment, net	120,068	115,106
Depreciation, depletion and amortization	10,600	10,500	$ 14,800
Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	54,045	49,105
Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	153,676	146,447
NACoal | Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	53,576	48,636
NACoal | Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	151,145	141,440
NACCO and Other | Coal Lands and Real Estate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	469	469
NACCO and Other | Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 2,531	$ 5,007