Quarterly Results of Operations (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 297,285,000	$ 221,714,000	$ 200,370,000	$ 177,413,000	$ 311,983,000	$ 228,614,000	$ 196,017,000	$ 196,052,000	$ 896,782,000	$ 932,666,000	$ 873,364,000
Gross profit	65,835,000	46,543,000	36,523,000	36,171,000	78,181,000	49,219,000	47,630,000	46,261,000	185,072,000	221,291,000	225,942,000
Earnings of unconsolidated mines	12,327,000	12,064,000	11,567,000	12,438,000	12,242,000	11,808,000	10,281,000	12,098,000	48,396,000	46,429,000	45,244,000
Operating profit	(73,156,000)	11,323,000	(3,891,000)	(585,000)	28,829,000	16,682,000	8,803,000	7,022,000	(66,309,000)	61,336,000	67,642,000
Income (loss) from continuing operations	(40,669,000)	7,699,000	(3,624,000)	(1,524,000)					(38,118,000)	44,450,000	42,163,000
Net income (loss)					22,556,000	12,325,000	5,147,000	4,422,000	(38,118,000)	44,450,000	108,698,000
Basic earnings (loss) per share:
Basic earnings per share	$ (5.57)	$ 1.02	$ 0.47	$ 0.19	$ 2,860,000	$ 1.54	$ 0.63	$ 0.53	$ (5.02)	$ 5.48	$ 12.97
Diluted earnings per share	$ (5.57)	$ 1.02	$ 0.47	$ 0.19	$ 2,850,000	$ 1.54	$ 0.63	$ 0.53	$ (5.02)	$ 5.47	$ 12.92
Reed Minerals goodwill impairment charge									0	3,973,000	0
U.S. Pension Plan
Basic earnings (loss) per share:
Curtailment gain		1,700,000				1,700,000			0	1,701,000	0
Selling, general and administrative expenses | Increase in estimated liability for certain frozen deferred compensation plans
Basic earnings (loss) per share:
Immaterial error correction			1,100,000
NACoal
Segment Reporting Information [Line Items]
Revenues	33,210,000	49,840,000	49,780,000	39,872,000	46,067,000	52,870,000	43,567,000	51,147,000	172,702,000	193,651,000	132,367,000
Gross profit									(3,139,000)	25,230,000	27,998,000
Operating profit	(100,228,000)	4,362,000	183,000	6,653,000	4,740,000	9,740,000	11,196,000	11,785,000	(89,030,000)	37,461,000	43,239,000
Income (loss) from continuing operations	(59,792,000)	3,185,000	(75,000)	5,705,000	5,589,000	7,794,000	8,952,000	9,591,000	(50,977,000)	31,926,000	32,770,000
NACoal | U.S. Pension Plan
Basic earnings (loss) per share:
Curtailment gain						1,600,000
HBB
Segment Reporting Information [Line Items]
Revenues	204,818,000	135,155,000	118,385,000	101,325,000	192,889,000	134,099,000	114,651,000	106,151,000	559,683,000	547,790,000	521,567,000
Gross profit									117,570,000	115,506,000	102,289,000
Operating profit	23,053,000	9,531,000	2,251,000	937,000	22,499,000	11,788,000	4,005,000	2,668,000	35,772,000	40,960,000	35,815,000
Income (loss) from continuing operations	15,427,000	6,008,000	1,359,000	350,000	14,180,000	7,427,000	1,985,000	1,501,000	23,144,000	25,093,000	21,200,000
KC
Segment Reporting Information [Line Items]
Revenues	61,314,000	37,551,000	32,804,000	36,876,000	75,324,000	42,618,000	38,380,000	39,711,000	168,545,000	196,033,000	224,695,000
Gross profit									71,621,000	80,972,000	95,832,000
Operating profit	5,123,000	(1,429,000)	(4,255,000)	(6,514,000)	3,142,000	(3,658,000)	(5,407,000)	(4,980,000)	(7,075,000)	(10,903,000)	(4,512,000)
Income (loss) from continuing operations	3,053,000	(966,000)	(2,657,000)	(4,033,000)	1,608,000	(2,822,000)	(2,403,000)	(3,267,000)	(4,603,000)	(6,884,000)	(3,087,000)
NACCO and Other
Segment Reporting Information [Line Items]
Gross profit									(461,000)	(469,000)	(278,000)
Operating profit	(1,027,000)	(1,073,000)	(2,004,000)	(1,352,000)	(1,543,000)	(1,155,000)	(1,099,000)	(2,436,000)	(5,456,000)	(6,233,000)	(7,000,000)
Income (loss) from continuing operations	(1,568,000)	(906,000)	(1,673,000)	(1,197,000)	(1,530,000)	(1,137,000)	(1,048,000)	(2,003,000)	(5,344,000)	(5,718,000)	(8,649,000)
NACCO and Other | U.S. Pension Plan
Basic earnings (loss) per share:
Curtailment gain						100,000
Eliminations
Segment Reporting Information [Line Items]
Revenues	(2,057,000)	(832,000)	(599,000)	(660,000)	(2,297,000)	(973,000)	(581,000)	(957,000)	(4,148,000)	(4,808,000)	(5,265,000)
Gross profit									(519,000)	52,000	101,000
Operating profit	(77,000)	(68,000)	(66,000)	(309,000)	(9,000)	(33,000)	108,000	(15,000)	(520,000)	51,000	100,000
Income (loss) from continuing operations	2,211,000	378,000	(578,000)	(2,349,000)	2,709,000	1,063,000	(2,339,000)	(1,400,000)	(338,000)	33,000	(71,000)
Reed Minerals
Basic earnings (loss) per share:
Reed Minerals goodwill impairment charge	4,000,000
Reed Minerals | NACoal
Basic earnings (loss) per share:
Reed Minerals long-lived asset impairment charge	$ 105,100,000