Correction of Errors in Previously Reported Financial Statements, (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2008
Current assets:
Cash and cash equivalents	$ 24,116	[1]	$ 26,808	[1]	$ 27,669	[1]	$ 19,441	[1]
Accounts receivable, net	204,419	[1]	189,772	[1]	147,255	[1]
Inventories	144,310	[1]	105,284	[1]
Prepaid expenses	15,220	[1]	12,992	[1]
Deferred income taxes	4,099	[1]	5,533	[1]
Income tax receivable	8,215	[1]	8,474	[1]
Other	6,096	[1]	6,211	[1]
Total current assets	406,475	[1]	355,074	[1]
Property, plant, equipment, and mineral rights and reserves:
Land	12,103	[1]	10,875	[1]
Mineral rights	52,482	[1]	65,018	[1]
Depreciable assets	484,753	[1]	452,647	[1]
Gross property, plant and equipment	549,338	[1]	528,540	[1]
Less: accumulated depreciation and depletion	275,770	[1]	256,860	[1]
Net property, plant and equipment	273,568	[1]	271,680	[1]	248,351	[1]
Goodwill	69,509	[1]	70,909	[1]	71,156
Intangible assets, net	36,871	[1]	41,869	[1]
Investment in and advances to affiliates and joint ventures	26,407	[1]	20,904	[1]
Available-for-sale securities	3,802	[1]	14,168	[1]
Deferred income taxes	8,098	[1]	9,147	[1]
Other assets	24,412	[1]	23,504	[1]
Total noncurrent assets	442,667	[1]	452,181	[1]
Total Assets	849,142	[1]	807,255	[1]	746,835	[1]
Current liabilities:
Accounts payable	56,451	[1]	51,394	[1]
Accrued income taxes	2,296	[1]	5,308	[1]
Accrued liabilities	59,252	[1]	55,786	[1]
Total current liabilities	117,999	[1]	112,488	[1]
Noncurrent liabilities:
Long-term debt	260,670	[1]	235,668	[1]
Pension liabilities	34,840	[1]	21,338	[1]
Deferred compensation	8,927	[1]	9,006	[1]
Deferred income taxes	12,672	[1]	16,254	[1]
Other long-term liabilities	19,148	[1]	18,442	[1]
Total noncurrent liabilities	336,257	[1]	300,708	[1]
Shareholders' Equity:
Common stock	320	[1]	320	[1]
Additional paid in capital	94,316	[1]	95,074	[1]
Retained earnings	314,278	[1]	278,519	[1]
Accumulated other comprehensive income (loss)	(14,719)	[1]	28,740	[1]
Less: Treasury stock	3,426	[1]	8,945	[1]
Total AMCOL shareholders' equity	390,769	[1]	393,708	[1]
Noncontrolling interest	4,117	[1]	351	[1]
Total equity	394,886	[1]	394,059	[1]	375,539	[1]	328,355
Total Liabilities and Shareholders' Equity	849,142	[1]	807,255	[1]
Previously reported [Member]
Current assets:
Cash and cash equivalents	23,700		27,300		27,700
Accounts receivable, net	206,800		194,000
Inventories	146,600		107,500
Prepaid expenses	15,700		12,600
Deferred income taxes	5,900		5,500
Income tax receivable	6,900		8,500
Other	6,700		6,200
Total current assets	412,300		361,600
Property, plant, equipment, and mineral rights and reserves:
Land	13,900		11,600
Mineral rights	41,900		51,400
Depreciable assets	482,300		454,400
Gross property, plant and equipment	538,100		517,400
Less: accumulated depreciation and depletion	275,500		256,900
Net property, plant and equipment	262,600		260,500
Goodwill	69,500		70,900
Intangible assets, net	36,600		42,600
Investment in and advances to affiliates and joint ventures	26,400		19,000
Available-for-sale securities	3,800		14,200
Deferred income taxes	7,800		7,600
Other assets	23,700		22,700
Total noncurrent assets	430,400		437,500
Total Assets	842,700		799,100
Current liabilities:
Accounts payable	56,400		53,200
Accrued income taxes	2,700		4,100
Accrued liabilities	59,000		55,200
Total current liabilities	118,100		112,500
Noncurrent liabilities:
Long-term debt	260,700		236,200
Pension liabilities	34,800		21,300
Deferred compensation	8,900		8,700
Deferred income taxes	800		400
Other long-term liabilities	19,200		19,600
Total noncurrent liabilities	324,400		286,200
Shareholders' Equity:
Common stock	300		300
Additional paid in capital	94,500		95,100
Retained earnings	319,600		283,200
Accumulated other comprehensive income (loss)	(15,000)		28,900
Less: Treasury stock	3,400		8,900
Total AMCOL shareholders' equity	396,000		398,600
Noncontrolling interest	4,200		1,800
Total equity	400,200		400,400
Total Liabilities and Shareholders' Equity	842,700		799,100
Adjustments [Member]
Current assets:
Cash and cash equivalents	400		(500)		0
Accounts receivable, net	(2,400)		(4,200)
Inventories	(2,300)		(2,200)
Prepaid expenses	(500)		400
Deferred income taxes	(1,800)
Income tax receivable	1,300
Other	(500)
Total current assets	(5,800)		(6,500)
Property, plant, equipment, and mineral rights and reserves:
Land	(1,800)		(700)
Mineral rights	10,600		13,600
Depreciable assets	2,400		(1,800)
Gross property, plant and equipment	11,200		11,100
Less: accumulated depreciation and depletion	300		0
Net property, plant and equipment	10,900		11,100
Intangible assets, net	300		(700)
Investment in and advances to affiliates and joint ventures			1,900
Deferred income taxes	300		1,600
Other assets	700		800
Total noncurrent assets	12,200		14,700
Total Assets	6,400		8,200
Current liabilities:
Accounts payable	100		(1,800)
Accrued income taxes	(400)		1,200
Accrued liabilities	200		600
Total current liabilities	(100)		0
Noncurrent liabilities:
Long-term debt			(500)
Deferred compensation			300
Deferred income taxes	11,900		15,900
Other long-term liabilities	(100)		(1,100)
Total noncurrent liabilities	11,800		14,600
Shareholders' Equity:
Additional paid in capital	(200)
Retained earnings	(5,300)		(4,700)
Accumulated other comprehensive income (loss)	300		(200)
Total AMCOL shareholders' equity	(5,200)		(4,900)
Noncontrolling interest	(100)		(1,500)
Total equity	(5,300)		(6,400)
Total Liabilities and Shareholders' Equity	6,400		8,200
Tax [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	0		0
Deferred income taxes	(1,800)
Income tax receivable	1,300
Total current assets	(500)		0
Property, plant, equipment, and mineral rights and reserves:
Gross property, plant and equipment	0		0
Net property, plant and equipment	0		0
Deferred income taxes	(400)
Total noncurrent assets	(400)		0
Total Assets	(900)		0
Current liabilities:
Accounts payable	0
Accrued income taxes	0		1,500
Total current liabilities	0		1,500
Noncurrent liabilities:
Deferred income taxes	(800)		100
Total noncurrent liabilities	(800)		100
Shareholders' Equity:
Retained earnings	(100)		(1,600)
Total AMCOL shareholders' equity	(100)		(1,600)
Total equity	(100)		(1,600)
Total Liabilities and Shareholders' Equity	(900)		0
Other [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	400		(500)
Accounts receivable, net	800		(2,400)
Inventories	(700)		(1,200)
Prepaid expenses	(500)		400
Deferred income taxes	0		0
Income tax receivable	0		0
Other	(500)		0
Total current assets	(500)		(3,700)
Property, plant, equipment, and mineral rights and reserves:
Land	(1,800)		(700)
Mineral rights	0		0
Depreciable assets	2,400		(1,800)
Gross property, plant and equipment	600		(2,500)
Less: accumulated depreciation and depletion	300		0
Net property, plant and equipment	300		(2,500)
Intangible assets, net	300		(700)
Investment in and advances to affiliates and joint ventures	0		1,900
Available-for-sale securities	0		0
Deferred income taxes	0		0
Other assets	0		300
Total noncurrent assets	600		(1,000)
Total Assets	100		(4,700)
Current liabilities:
Accounts payable	100		(1,100)
Accrued income taxes	(100)		(200)
Accrued liabilities	600		200
Total current liabilities	600		(1,100)
Noncurrent liabilities:
Long-term debt	0		(500)
Pension liabilities	0		0
Deferred compensation	0		300
Deferred income taxes	100		0
Other long-term liabilities	(100)		(1,100)
Total noncurrent liabilities	0		(1,300)
Shareholders' Equity:
Common stock	0		0
Additional paid in capital	0		0
Retained earnings	(400)		(900)
Accumulated other comprehensive income (loss)	(100)		(100)
Less: Treasury stock	0		0
Total AMCOL shareholders' equity	(500)		(1,000)
Noncontrolling interest	0		(1,300)
Total equity	(500)		(2,300)
Total Liabilities and Shareholders' Equity	100		(4,700)
Spain [Member]
Property, plant, equipment, and mineral rights and reserves:
Less: accumulated depreciation and depletion			0
Spain [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	0		0
Accounts receivable, net	(1,600)		(400)
Inventories	(1,800)		(1,000)
Total current assets	(3,400)		(1,400)
Property, plant, equipment, and mineral rights and reserves:
Gross property, plant and equipment	0		0
Net property, plant and equipment	0		0
Total noncurrent assets	0		0
Total Assets	(3,400)		(1,400)
Current liabilities:
Accounts payable	0		0
Accrued income taxes	(300)		(100)
Accrued liabilities	(800)		100
Total current liabilities	(1,100)		0
Noncurrent liabilities:
Total noncurrent liabilities	0
Shareholders' Equity:
Retained earnings	(2,500)		(1,400)
Accumulated other comprehensive income (loss)	200
Total AMCOL shareholders' equity	(2,300)		(1,400)
Total equity	(2,300)		(1,400)
Total Liabilities and Shareholders' Equity	(3,400)		(1,400)
Poland [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	0		0
Accounts receivable, net	(900)		(300)
Total current assets	(900)		(300)
Property, plant, equipment, and mineral rights and reserves:
Gross property, plant and equipment	0		0
Net property, plant and equipment	0		0
Total noncurrent assets	0		0
Total Assets	(900)		(300)
Current liabilities:
Accounts payable	0
Accrued liabilities	700		300
Total current liabilities	700		300
Noncurrent liabilities:
Total noncurrent liabilities	0		0
Shareholders' Equity:
Retained earnings	(1,800)		(600)
Accumulated other comprehensive income (loss)	200
Total AMCOL shareholders' equity	(1,600)		(600)
Total equity	(1,600)		(600)
Total Liabilities and Shareholders' Equity	(900)		(300)
South Africa [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	0		0
Inventories	200
Total current assets	200		0
Property, plant, equipment, and mineral rights and reserves:
Mineral rights	10,600		13,600
Gross property, plant and equipment	10,600		13,600
Net property, plant and equipment	10,600		13,600
Deferred income taxes	700		1,600
Total noncurrent assets	11,300		15,200
Total Assets	11,500		15,200
Current liabilities:
Accounts payable	0		0
Total current liabilities	0		0
Noncurrent liabilities:
Deferred income taxes	12,600		15,800
Total noncurrent liabilities	12,600		15,800
Shareholders' Equity:
Additional paid in capital	(200)
Retained earnings	(800)		(300)
Accumulated other comprehensive income (loss)			(100)
Total AMCOL shareholders' equity	(1,000)		(400)
Noncontrolling interest	(100)		(200)
Total equity	(1,100)		(600)
Total Liabilities and Shareholders' Equity	11,500		15,200
Malaysia [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	0		0
Accounts receivable, net	(700)		(1,100)
Total current assets	(700)		(1,100)
Property, plant, equipment, and mineral rights and reserves:
Gross property, plant and equipment	0		0
Net property, plant and equipment	0		0
Other assets	700		500
Total noncurrent assets	700		500
Total Assets	0		(600)
Current liabilities:
Accounts payable	0		0
Accrued income taxes			(200)
Accrued liabilities	(300)
Total current liabilities	(300)		(200)
Noncurrent liabilities:
Deferred income taxes	0
Total noncurrent liabilities	0		0
Shareholders' Equity:
Retained earnings	300		(400)
Total AMCOL shareholders' equity	300		(400)
Total equity	300		(400)
Total Liabilities and Shareholders' Equity	0		(600)
Dong Ming [Member] | Adjustments [Member]
Current assets:
Cash and cash equivalents	0		0
Total current assets	0		0
Property, plant, equipment, and mineral rights and reserves:
Gross property, plant and equipment	0		0
Net property, plant and equipment	0		0
Total noncurrent assets	0		0
Total Assets	0		0
Current liabilities:
Accounts payable	0		(700)
Accrued income taxes			200
Total current liabilities	0		(500)
Noncurrent liabilities:
Total noncurrent liabilities	0		0
Shareholders' Equity:
Retained earnings	0		500
Total AMCOL shareholders' equity	0		500
Total equity	0		500
Total Liabilities and Shareholders' Equity	$ 0		$ 0

[1] Restated