Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues	$ 239,107	$ 221,714		$ 629,341	$ 599,497
Operating profit (loss)	5,760	11,323		10,289	6,847
Net income (loss)	3,141	7,699		3,893	2,551
Cost of sales	196,892	175,171		513,556	480,260
Revision of estimated cash flows	7,500			7,526
Prior period accounting error	47,551	46,373		139,186	145,792
NACoal (a)
Segment Reporting Information [Line Items]
Cost of sales	500
Operating segments | NACoal (a)
Segment Reporting Information [Line Items]
Revenues	42,704	49,840		121,965	139,492
Operating profit (loss)	(4,010)	4,362		3,579	11,198
Net income (loss)	(5,345)	3,185		3,401	8,815
Operating segments | HBB
Segment Reporting Information [Line Items]
Revenues	163,291	135,155		416,082	354,865
Operating profit (loss)	11,643	9,531		16,711	12,719
Net income (loss)	6,378	6,008		8,614	7,717
Operating segments | KC
Segment Reporting Information [Line Items]
Revenues	34,708	37,551		94,457	107,231
Operating profit (loss)	(843)	(1,429)		(6,860)	(12,198)
Net income (loss)	(550)	(966)		(4,290)	(7,656)
Operating segments | NACCO and Other (b)
Segment Reporting Information [Line Items]
Operating profit (loss)	(1,142)	(1,073)		(3,267)	(4,429)
Net income (loss)	(774)	(906)		(2,710)	(3,776)
Eliminations
Segment Reporting Information [Line Items]
Revenues	(1,596)	(832)		(3,163)	(2,091)
Operating profit (loss)	112	(68)		126	(443)
Net income (loss)	$ 3,432	$ 378		$ (1,122)	$ (2,549)
Correction of Prior Period Accounting | NACCO and Other (b)
Segment Reporting Information [Line Items]
Prior period accounting error			$ 1,100