Employee Benefit Plans (Details 6) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Hedge Funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	$ 3,897	$ 2,167	$ 1,596
Fair Value Measurements Recurring [Member]
Fair value of pension plan assets
Fair value of pension plan assets	34,466	35,755
Fair Value Measurements Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	11,593	10,841
Fair Value Measurements Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	18,976	22,747
Fair Value Measurements Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	3,897	2,167
Fair Value Measurements Recurring [Member] \| Short term investment funds [Member]
Fair value of pension plan assets
Fair value of pension plan assets	727	612
Fair Value Measurements Recurring [Member] \| Short term investment funds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Short term investment funds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	727	612
Fair Value Measurements Recurring [Member] \| Short term investment funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| US equity securities [Member]
Fair value of pension plan assets
Fair value of pension plan assets	11,244	10,781
Fair Value Measurements Recurring [Member] \| US equity securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| US equity securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	11,244	10,781
Fair Value Measurements Recurring [Member] \| US equity securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| International equity securities [Member]
Fair value of pension plan assets
Fair value of pension plan assets	5,959	9,489
Fair Value Measurements Recurring [Member] \| International equity securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	2,028	3,367
Fair Value Measurements Recurring [Member] \| International equity securities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	3,931	6,122
Fair Value Measurements Recurring [Member] \| International equity securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| AMCOL International common stock [Member]
Fair value of pension plan assets
Fair value of pension plan assets	1,880	2,170
Fair Value Measurements Recurring [Member] \| AMCOL International common stock [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	1,880	2,170
Fair Value Measurements Recurring [Member] \| AMCOL International common stock [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| AMCOL International common stock [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Governmental agencies [Member]
Fair value of pension plan assets
Fair value of pension plan assets	1,011	1,774
Fair Value Measurements Recurring [Member] \| Governmental agencies [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	1,011	831
Fair Value Measurements Recurring [Member] \| Governmental agencies [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	943
Fair Value Measurements Recurring [Member] \| Governmental agencies [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Corporate bonds [Member]
Fair value of pension plan assets
Fair value of pension plan assets	4,981	2,477
Fair Value Measurements Recurring [Member] \| Corporate bonds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	4,981	2,477
Fair Value Measurements Recurring [Member] \| Corporate bonds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Corporate bonds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Guaranteed investment contracts [Member]
Fair value of pension plan assets
Fair value of pension plan assets	2,473	3,633
Fair Value Measurements Recurring [Member] \| Guaranteed investment contracts [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Guaranteed investment contracts [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	2,473	3,633
Fair Value Measurements Recurring [Member] \| Guaranteed investment contracts [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Real estate index funds [Member]
Fair value of pension plan assets
Fair value of pension plan assets	601	656
Fair Value Measurements Recurring [Member] \| Real estate index funds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Real estate index funds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	601	656
Fair Value Measurements Recurring [Member] \| Real estate index funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Commodities linked funds [Member]
Fair value of pension plan assets
Fair value of pension plan assets	1,693	1,996
Fair Value Measurements Recurring [Member] \| Commodities linked funds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	1,693	1,996
Fair Value Measurements Recurring [Member] \| Commodities linked funds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Commodities linked funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Hedge Funds [Member]
Fair value of pension plan assets
Fair value of pension plan assets	3,897	2,167
Fair Value Measurements Recurring [Member] \| Hedge Funds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Hedge Funds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	0	0
Fair Value Measurements Recurring [Member] \| Hedge Funds [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of pension plan assets
Fair value of pension plan assets	$ 3,897	$ 2,167

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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