Business Segments (Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues from external customers									$ 104,778	$ 111,081	$ 147,998
Gross profit (loss)	$ 5,289	$ 2,475	$ 4,597	$ 4,558	$ 2,230	$ 1,647	$ 2,237	$ 5,968	16,919	12,082	(11,232)
Earnings of unconsolidated mines	16,734	16,197	13,475	14,955	14,453	15,102	13,035	12,648	61,361	55,238	48,432
Selling, general and administrative expenses, including Amortization of intangible assets									49,614	51,366	42,711
Operating profit (loss)	6,506	6,989	9,513	9,806	(707)	(12,779)	3,526	8,301	32,814	(1,659)	(3,727)
Operating Segments | NACoal
Segment Reporting Information [Line Items]
Revenues from external customers	26,437	21,941	28,100	28,300	25,303	32,402	23,089	30,287	104,778	111,081	147,998
Gross profit (loss)									17,198	12,341	(10,816)
Selling, general and administrative expenses, including Amortization of intangible assets									42,516	44,347	38,867
Operating profit (loss)	8,550	8,925	10,876	11,326	1,966	(10,912)	4,823	9,742	39,677	5,619	521
NACCO and Other | NACCO and Other
Segment Reporting Information [Line Items]
Gross profit (loss)									(279)	(259)	(416)
Selling, general and administrative expenses, including Amortization of intangible assets									7,098	7,019	3,844
Operating profit (loss)	$ (2,044)	$ (1,936)	$ (1,363)	$ (1,520)	$ (2,673)	$ (1,867)	$ (1,297)	$ (1,441)	$ (6,863)	$ (7,278)	$ (4,248)