Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 24,116	[1]	$ 26,808	[1]
Accounts receivable, net	204,419	[1]	189,772	[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 taxes 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]
Goodwill	69,509	[1]	70,909	[1]
Intangible assets	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]
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 tax	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, par value $.01 per share, 100,000,000 shares authorized; 32,015,771 shares issued in 2011 and 2010	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]
Stockholders' equity before treasury stock	394,195	[1]	402,653	[1]
Less: Treasury stock (286,802 and 768,946 shares in 2011 and 2010, respectively)	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]
Total Liabilities and Shareholders' Equity	$ 849,142	[1]	$ 807,255	[1]

[1] Restated