Restatement and Revision of Previously Issued Consolidated Financial Statements - Consolidated Balance Sheets (Details) $ / shares in Units, shares in Thousands, $ in Thousands	Dec. 31, 2019 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Current assets
Cash and cash equivalents	$ 2,142	$ 1,559	$ 1,029	$ 1,636	$ 4,420	$ 1,567	$ 1,393	$ 1,784
Trade receivables, net	108,381	103,091	86,268	79,102	98,361	112,309	76,132	79,358
Inventory	109,806	161,043	121,472	120,707	122,808	155,744	138,721	132,749
Prepaid expenses and other current assets	11,345	14,086	16,412	17,379	15,396	12,595	14,569	14,615
Current assets of discontinued operations	5,383	22,830	21,255	24,692	27,879	32,185	30,704	29,086
Total current assets	237,057	302,609	246,436	243,516	268,864	314,400	261,519	257,592
Property, plant and equipment, net	22,324	22,193	21,649	20,984	20,842	20,988	19,088	17,643	$ 15,979
Goodwill	6,253	6,253	6,253	6,253	6,253	6,253	6,253	6,253
Other intangible assets, net	3,141	3,483	3,828	4,174	4,519	4,864	5,209	5,555
Deferred income taxes	6,248	5,640	3,754	3,166	5,794	7,704	8,877	10,419
Deferred costs	10,941	8,804	8,564	8,316	7,868	10,153	9,825	10,187
Other non-current assets	2,085	1,553	1,984	2,403	2,672	3,282	3,178	3,068
Non-current assets of discontinued operations	614	1,744	4,420	4,446	4,606	5,313	5,688	5,661
Total assets	288,663	352,279	296,888	293,258	321,418	372,957	319,637	316,378
Current liabilities
Accounts payable	111,348	140,011	86,199	73,720	119,271	131,620	92,488	96,924
Accounts payable to NACCO Industries, Inc.	496	220	220	2,425	2,416	2,480	2,769	7,814
Revolving credit agreements	23,497	50,152	51,505	54,812	11,624	60,083	66,326	63,308
Accrued compensation	15,027	14,650	11,725	8,398	15,878	15,421	11,984	9,238
Accrued product returns	8,697	8,266	8,224	9,314	10,698	9,601	9,648	10,815
Other current liabilities	12,534	25,880	21,382	17,705	22,922	22,488	15,769	21,227
Current liabilities of discontinued operations	29,723	24,713	20,048	21,473	22,820	29,693	26,830	21,509
Total current liabilities	201,322	263,892	199,303	187,847	205,629	271,386	225,814	230,835
Revolving credit agreements	35,000	30,000	30,000	30,000	35,000	30,000	30,000	20,000
Other long-term liabilities	16,075	14,258	14,699	18,619	22,011	22,343	21,654	21,831
Non-current liabilities of discontinued operations	0	1,585	3,697	3,834	1,960	2,293	2,416	2,565
Total liabilities	252,397	309,735	247,699	240,300	264,600	326,022	279,884	275,231
Stockholders’ equity
Preferred stock, par value $0.01 per share	0				0
Capital in excess of par value	54,509				51,714
Treasury stock	(5,960)	(5,960)	(2,334)	0	0	0	0	0
Retained earnings	3,710	12,231	15,646	17,506	22,068	9,373	3,397	5,683
Accumulated other comprehensive loss	(16,132)	(18,009)	(17,604)	(17,207)	(17,101)	(13,941)	(14,502)	(13,724)
Total stockholders’ equity	36,266	42,544	49,189	52,958	56,818	46,935	39,753	41,147
Total liabilities and stockholders' equity	$ 288,663	352,279	296,888	293,258	$ 321,418	372,957	319,637	316,378
Preferred stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Class A Common Stock
Stockholders’ equity
Common stock	$ 98	95	95	95	$ 93	92	92	92
Common stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Common stock, shares, issued (in shares) | shares	9,805				9,291
Class B Common Stock
Stockholders’ equity
Common stock	$ 41	44	44	44	$ 44	45	45	45
Capital in excess of par value		54,143	53,342	52,520		51,366	50,721	49,051
Common stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Common stock, shares, issued (in shares) | shares	4,076				4,422
Common stock, convertible conversion ratio	1				1
As Previously Reported
Current assets
Cash and cash equivalents	$ 2,142	1,866	1,131	1,721	$ 4,420	2,139	1,962	2,389
Trade receivables, net	113,781	106,135	89,579	92,534	100,821	113,683	77,623	88,579
Inventory	109,621	181,847	140,817	142,261	122,697	183,831	165,237	157,622
Prepaid expenses and other current assets	23,102	22,445	24,078	16,373	22,332	20,766	20,996	11,848
Current assets of discontinued operations	5,383	0	0	0	27,879	0	0	0
Total current assets	254,029	312,293	255,605	252,889	278,149	320,419	265,818	260,438
Property, plant and equipment, net	22,324	22,653	23,204	22,566	20,842	23,309	21,839	20,597
Goodwill	6,253	6,253	6,253	6,253	6,253	6,253	6,253	6,253
Other intangible assets, net	3,141	3,483	3,828	4,174	4,519	4,864	5,209	5,555
Deferred income taxes	3,853	6,161	6,169	5,493	5,518	10,450	10,894	12,200
Deferred costs	10,941	8,925	8,683	8,447	7,868	10,306	9,973	10,347
Other non-current assets	2,085	1,561	1,997	2,424	2,672	3,322	3,282	3,224
Non-current assets of discontinued operations	614	0	0	0	4,606	0	0	0
Total assets	303,240	361,329	305,739	302,246	330,427	378,923	323,268	318,614
Current liabilities
Accounts payable	111,117	147,206	91,737	80,649	119,264	143,955	103,461	108,185
Accounts payable to NACCO Industries, Inc.	496	220	220	2,425	2,416	2,480	2,769	9,285
Revolving credit agreements	23,497	59,702	58,955	62,212	11,624	69,883	75,476	65,508
Accrued compensation	14,277	15,568	12,091	8,903	15,525	16,575	12,531	9,833
Accrued product returns	8,697	8,266	8,224	9,314	10,698	9,601	9,648	10,815
Other current liabilities	12,873	30,651	27,930	24,109	24,554	27,139	19,099	22,751
Current liabilities of discontinued operations	29,723	0	0	0	22,820	0	0	0
Total current liabilities	200,680	261,613	199,157	187,612	206,901	269,633	222,984	226,377
Revolving credit agreements	35,000	30,000	32,000	32,000	35,000	30,000	30,000	20,000
Other long-term liabilities	12,501	14,961	15,485	19,555	21,128	24,840	24,274	24,600
Non-current liabilities of discontinued operations		0	0	0	1,960	0	0	0
Total liabilities	248,181	306,574	246,642	239,167	264,989	324,473	277,258	270,977
Stockholders’ equity
Preferred stock, par value $0.01 per share	0				0
Capital in excess of par value	54,344				51,714
Treasury stock	(5,960)	(5,960)	(2,334)		0	0	0	0
Retained earnings	22,524	24,955	25,773	27,959	30,897	17,031	10,152	12,191
Accumulated other comprehensive loss	(15,988)	(18,522)	(17,823)	(17,539)	(17,310)	(14,084)	(15,000)	(13,742)
Total stockholders’ equity	55,059	54,755	59,097	63,079	65,438	54,450	46,010	47,637
Total liabilities and stockholders' equity	$ 303,240	361,329	305,739	302,246	$ 330,427	378,923	323,268	318,614
Preferred stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
As Previously Reported | Class A Common Stock
Stockholders’ equity
Common stock	$ 98	95	95	95	$ 93	92	92	92
Common stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Common stock, shares, issued (in shares) | shares	9,805				9,291
As Previously Reported | Class B Common Stock
Stockholders’ equity
Common stock	$ 41	44	44	44	$ 44	45	45	45
Capital in excess of par value		54,143	53,342	52,520		51,366	50,721	49,051
Common stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Common stock, shares, issued (in shares) | shares	4,076				4,422
Common stock, convertible conversion ratio	1				1
Restatement Impacts
Current assets
Cash and cash equivalents	$ 0	0	0	0	$ 0	0	0	0
Trade receivables, net	(5,400)	(2,179)	(2,446)	(2,768)	(2,460)	(351)	(411)	(191)
Inventory	185	0	0	0	111	0	0	0
Prepaid expenses and other current assets	(11,757)	(7,505)	(6,723)	(6,605)	(6,936)	(5,668)	(3,888)	(2,655)
Current assets of discontinued operations	0	0	0	0	0	0	0	0
Total current assets	(16,972)	(9,684)	(9,169)	(9,373)	(9,285)	(6,019)	(4,299)	(2,846)
Property, plant and equipment, net	0	0	0	0	0	0	0	0
Goodwill	0	0	0	0	0	0	0	0
Other intangible assets, net	0	0	0	0	0	0	0	0
Deferred income taxes	2,395	634	318	385	276	53	668	610
Deferred costs	0	0	0	0	0	0	0	0
Other non-current assets	0	0	0	0	0	0	0	0
Non-current assets of discontinued operations	0	0	0	0	0	0	0	0
Total assets	(14,577)	(9,050)	(8,851)	(8,988)	(9,009)	(5,966)	(3,631)	(2,236)
Current liabilities
Accounts payable	231	16	0	0	7	0	0	0
Accounts payable to NACCO Industries, Inc.	0	0	0	0	0	0	0	0
Revolving credit agreements	0	0	0	0	0	0	0	0
Accrued compensation	750	389	387	370	353	356	325	338
Accrued product returns	0	0	0	0	0	0	0	0
Other current liabilities	(339)	1,874	(241)	(135)	(1,632)	1,397	2,505	4,120
Current liabilities of discontinued operations	0	0	0	0	0	0	0	0
Total current liabilities	642	2,279	146	235	(1,272)	1,753	2,830	4,458
Revolving credit agreements	0	0	0	0	0	0	0	0
Other long-term liabilities	3,574	882	911	898	883	(204)	(204)	(204)
Non-current liabilities of discontinued operations		0	0	0	0	0	0	0
Total liabilities	4,216	3,161	1,057	1,133	(389)	1,549	2,626	4,254
Stockholders’ equity
Preferred stock, par value $0.01 per share	0				0
Capital in excess of par value	165				0
Treasury stock	0	0	0		0	0	0	0
Retained earnings	(18,814)	(12,724)	(10,127)	(10,453)	(8,829)	(7,658)	(6,755)	(6,508)
Accumulated other comprehensive loss	(144)	513	219	332	209	143	498	18
Total stockholders’ equity	(18,793)	(12,211)	(9,908)	(10,121)	(8,620)	(7,515)	(6,257)	(6,490)
Total liabilities and stockholders' equity	$ (14,577)	(9,050)	(8,851)	(8,988)	$ (9,009)	(5,966)	(3,631)	(2,236)
Preferred stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Restatement Impacts | Class A Common Stock
Stockholders’ equity
Common stock	$ 0	0	0	0	$ 0	0	0	0
Common stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Common stock, shares, issued (in shares) | shares	9,805				9,291
Restatement Impacts | Class B Common Stock
Stockholders’ equity
Common stock	$ 0	0	0	0	$ 0	0	0	0
Capital in excess of par value		$ 0	$ 0	$ 0		$ 0	$ 0	$ 0
Common stock, par value (in usd per share) | $ / shares	$ 0.01				$ 0.01
Common stock, shares, issued (in shares) | shares	4,076				4,422
Common stock, convertible conversion ratio	1				1