Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Revenues	$ 196,500	$ 200,370	$ 390,234	$ 377,783
Operating profit (loss)	1,288	(3,891)	4,529	(4,476)
Net income (loss)	(275)	(3,624)	752	(5,148)
Prior period accounting error	45,219	50,990	91,635	99,419
Operating segments | NACoal
Segment Reporting Information [Line Items]
Revenues	37,942	49,780	79,261	89,652
Operating profit (loss)	2,382	183	7,589	6,836
Net income (loss)	4,199	(75)	8,746	5,630
Operating segments | HBB
Segment Reporting Information [Line Items]
Revenues	129,498	118,385	252,791	219,710
Operating profit (loss)	2,880	2,251	5,068	3,188
Net income (loss)	1,618	1,359	2,236	1,709
Operating segments | KC
Segment Reporting Information [Line Items]
Revenues	29,782	32,804	59,749	69,680
Operating profit (loss)	(2,972)	(4,255)	(6,017)	(10,769)
Net income (loss)	(1,847)	(2,657)	(3,740)	(6,690)
Operating segments | NACCO and Other (a)
Segment Reporting Information [Line Items]
Operating profit (loss)	(836)	(2,004)	(2,125)	(3,356)
Net income (loss)	(697)	(1,673)	(1,936)	(2,870)
Eliminations
Segment Reporting Information [Line Items]
Revenues	(722)	(599)	(1,567)	(1,259)
Operating profit (loss)	(166)	(66)	14	(375)
Net income (loss)	$ (3,548)	(578)	$ (4,554)	$ (2,927)
Correction of Prior Period Accounting | NACCO and Other (a)
Segment Reporting Information [Line Items]
Prior period accounting error		$ 1,100