CORRECTION OF ERRORS IN PREVIOUSLY REPORTED FINANCIAL STATEMENTS, (Details 1) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Continuing Operations
Net sales	$ 235.5	[1]	$ 218.6	[1]
Cost of sales	170.8	[1]	160.7	[1]
Gross profit	64.7	[1]	57.9	[1]
Selling, general and administrative expenses	43.3	[1]	38.9	[1]
Operating profit	21.4	[1]	19.0	[1]
Other income (expense):
Interest expense, net	(2.7)	[1]	(2.6)	[1]
Other, net	(2.1)	[1]	(0.4)	[1]
Total other income (expense), net	(4.8)	[1]	(3.0)	[1]
Income before income taxes and income (loss) from affiliates and joint ventures	16.6	[1]	16.0	[1]
Income tax expense (benefit)	4.4	[1]	3.8	[1]
Income before income (loss) from affiliates and joint ventures	12.2	[1]	12.2	[1]
Income (loss) from affiliates and joint ventures	1.3	[1]	1.0	[1]
Income (loss) from continuing operations	13.5	[1]	13.2	[1]
Discontinued Operations
Income (loss) on discontinued operations	0	[1]	(0.1)	[1]
Net income (loss)	13.5	[1]	13.1	[1]
Net income (loss) attributable to noncontrolling interests	0.1	[1]	0	[1]
Net income (loss) attributable to AMCOL shareholders	13.4	[1]	13.1	[1]
Weighted average common shares outstanding (in shares)	32.0	[1]	31.5	[1]
Weighted average common and common equivalent shares outstanding (in shares)	32.3	[1]	32.0	[1]
Amounts attributable to AMCOL shareholders
Income from continuing operations, net of tax	13.4	[1]	13.2	[1]
Discontinued operations, net of tax	0	[1]	(0.1)	[1]
Net income	13.4	[1]	13.1	[1]
Basic earnings (loss) per share:
Continuing operations (in dollars per share)	$ 0.42	[1]	$ 0.42	[1]
Discontinued operations (in dollars per share)	$ 0	[1]	$ 0	[1]
Net income (in dollars per share)	$ 0.42	[1]	$ 0.42	[1]
Diluted earnings (loss) per share:
Continuing operations (in dollars per share)	$ 0.41	[1]	$ 0.41	[1]
Discontinued operations (in dollars per share)	$ 0	[1]	$ 0	[1]
Net income (in dollars per share)	$ 0.41	[1]	$ 0.41	[1]
Previously reported [Member]
Continuing Operations
Net sales	235.8		217.8
Cost of sales	170.7		160.1
Gross profit	65.1		57.7
Selling, general and administrative expenses	43.6		39.1
Operating profit	21.5		18.6
Other income (expense):
Interest expense, net	(2.7)		(2.7)
Other, net	(2.1)		(0.4)
Total other income (expense), net	(4.8)		(3.1)
Income before income taxes and income (loss) from affiliates and joint ventures	16.7		15.5
Income tax expense (benefit)	4.8		4.3
Income before income (loss) from affiliates and joint ventures	11.9		11.2
Income (loss) from affiliates and joint ventures	1.2		1.1
Income (loss) from continuing operations	13.1		12.3
Discontinued Operations
Income (loss) on discontinued operations	(0.2)		(0.1)
Net income (loss)	12.9		12.2
Net income (loss) attributable to noncontrolling interests	0.1		0
Net income (loss) attributable to AMCOL shareholders	12.8		12.2
Weighted average common shares outstanding (in shares)	32.0		31.5
Weighted average common and common equivalent shares outstanding (in shares)	32.3		32.0
Amounts attributable to AMCOL shareholders
Income from continuing operations, net of tax	13.0		12.3
Discontinued operations, net of tax	(0.2)		(0.1)
Net income	12.8		12.2
Basic earnings (loss) per share:
Continuing operations (in dollars per share)	$ 0.41		$ 0.39
Discontinued operations (in dollars per share)	$ (0.01)		$ 0
Net income (in dollars per share)	$ 0.40		$ 0.39
Diluted earnings (loss) per share:
Continuing operations (in dollars per share)	$ 0.41		$ 0.38
Discontinued operations (in dollars per share)	$ (0.01)		$ 0
Net income (in dollars per share)	$ 0.40		$ 0.38
Adjustments [Member]
Continuing Operations
Net sales	(0.3)		0.8
Cost of sales	0.1		0.6
Gross profit	(0.4)		0.2
Selling, general and administrative expenses	(0.3)		(0.2)
Operating profit	(0.1)		0.4
Other income (expense):
Interest expense, net			0.1
Other, net	0
Total other income (expense), net	0		0.1
Income before income taxes and income (loss) from affiliates and joint ventures	(0.1)		0.5
Income tax expense (benefit)	(0.4)		(0.5)
Income before income (loss) from affiliates and joint ventures	0.3		1.0
Income (loss) from affiliates and joint ventures	0.1		(0.1)
Income (loss) from continuing operations	0.4		0.9
Discontinued Operations
Income (loss) on discontinued operations	0.2
Net income (loss)	0.6		0.9
Net income (loss) attributable to AMCOL shareholders	0.6		0.9
Weighted average common shares outstanding (in shares)	32.0		31.5
Weighted average common and common equivalent shares outstanding (in shares)	32.3		32.0
Amounts attributable to AMCOL shareholders
Income from continuing operations, net of tax	0.4		0.9
Discontinued operations, net of tax	0.2		0
Net income	0.6		0.9
Basic earnings (loss) per share:
Continuing operations (in dollars per share)	$ 0.01		$ 0.03
Discontinued operations (in dollars per share)	$ 0.01		$ 0
Net income (in dollars per share)	$ 0.02		$ 0.03
Diluted earnings (loss) per share:
Continuing operations (in dollars per share)	$ 0		$ 0.03
Discontinued operations (in dollars per share)	$ 0.01		$ 0
Net income (in dollars per share)	$ 0.01		$ 0.03
Tax [Member] | Adjustments [Member]
Continuing Operations
Net sales	0		0
Gross profit	0		0
Operating profit	0		0
Other income (expense):
Total other income (expense), net	0		0
Income before income taxes and income (loss) from affiliates and joint ventures	0		0
Income tax expense (benefit)	(0.3)		(0.5)
Income before income (loss) from affiliates and joint ventures	0.3		0.5
Income (loss) from affiliates and joint ventures			(0.1)
Income (loss) from continuing operations	0.3		0.4
Discontinued Operations
Net income (loss)	0.3		0.4
Net income (loss) attributable to AMCOL shareholders	0.3		0.4
Other [Member] | Adjustments [Member]
Continuing Operations
Net sales	(0.3)		0.2
Cost of sales	(0.2)		(0.3)
Gross profit	(0.1)		0.5
Selling, general and administrative expenses	(0.1)		(0.2)
Operating profit	0		0.7
Other income (expense):
Interest expense, net	0		0.1
Other, net	0		0
Total other income (expense), net	0		0.1
Income before income taxes and income (loss) from affiliates and joint ventures	0		0.8
Income tax expense (benefit)	(0.1)		(0.2)
Income before income (loss) from affiliates and joint ventures	0.1		1.0
Income (loss) from affiliates and joint ventures	0.1		0
Income (loss) from continuing operations	0.2		1.0
Discontinued Operations
Income (loss) on discontinued operations	0.2		0
Net income (loss)	0.4		1.0
Net income (loss) attributable to noncontrolling interests	0		0
Net income (loss) attributable to AMCOL shareholders	0.4		1.0
Spain [Member] | Adjustments [Member]
Continuing Operations
Net sales	0		0
Cost of sales	0.4		0.3
Gross profit	(0.4)		(0.3)
Selling, general and administrative expenses	(0.2)
Operating profit	(0.2)		(0.3)
Other income (expense):
Total other income (expense), net	0		0
Income before income taxes and income (loss) from affiliates and joint ventures	(0.2)		(0.3)
Income tax expense (benefit)	0.1
Income before income (loss) from affiliates and joint ventures	(0.3)		(0.3)
Income (loss) from continuing operations	(0.3)		(0.3)
Discontinued Operations
Net income (loss)	(0.3)		(0.3)
Net income (loss) attributable to AMCOL shareholders	(0.3)		(0.3)
Poland [Member] | Adjustments [Member]
Continuing Operations
Net sales	0		0
Cost of sales	(0.2)		0.5
Gross profit	0.2		(0.5)
Operating profit	0.2		(0.5)
Other income (expense):
Total other income (expense), net	0		0
Income before income taxes and income (loss) from affiliates and joint ventures	0.2		(0.5)
Income before income (loss) from affiliates and joint ventures	0.2		(0.5)
Income (loss) from continuing operations	0.2		(0.5)
Discontinued Operations
Net income (loss)	0.2		(0.5)
Net income (loss) attributable to AMCOL shareholders	0.2		(0.5)
South Africa [Member] | Adjustments [Member]
Continuing Operations
Net sales	0		0
Cost of sales	0.1		0.1
Gross profit	(0.1)		(0.1)
Operating profit	(0.1)		(0.1)
Other income (expense):
Total other income (expense), net	0		0
Income before income taxes and income (loss) from affiliates and joint ventures	(0.1)		(0.1)
Income tax expense (benefit)	(0.1)		0.1
Income before income (loss) from affiliates and joint ventures	0		(0.2)
Income (loss) from continuing operations	0		(0.2)
Discontinued Operations
Net income (loss)	0		(0.2)
Net income (loss) attributable to AMCOL shareholders	0		(0.2)
Malaysia [Member] | Adjustments [Member]
Continuing Operations
Net sales			0.6
Gross profit			0.6
Operating profit			0.6
Other income (expense):
Total other income (expense), net			0
Income before income taxes and income (loss) from affiliates and joint ventures			0.6
Income tax expense (benefit)			0.1
Income before income (loss) from affiliates and joint ventures			0.5
Income (loss) from continuing operations			0.5
Discontinued Operations
Net income (loss)			0.5
Net income (loss) attributable to AMCOL shareholders			$ 0.5

[1] Restated