CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (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	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]
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]
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]
Dividends declared per share (in dollars per share)	$ 0.18	[1]	$ 0.18	[1]

[1] Restated