CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Continuing Operations
Net sales	$ 253.3	$ 248.1	$ 746.3	$ 709.8
Cost of sales	183.9	177.5	537.7	518.8
Gross profit	69.4	70.6	208.6	191.0
Selling, general and administrative expenses	41.8	44.0	128.7	124.1
Operating profit	27.6	26.6	79.9	66.9
Other income (expense):
Interest expense, net	(2.5)	(2.8)	(7.9)	(8.1)
Other, net	0	(0.2)	(2.7)	(0.1)
Total other income (expense), net	(2.5)	(3.0)	(10.6)	(8.2)
Income before income taxes and income (loss) from affiliates and joint ventures	25.1	23.6	69.3	58.7
Income tax expense	7.4	5.3	19.3	14.9
Income before income (loss) from affiliates and joint ventures	17.7	18.3	50.0	43.8
Income (loss) from affiliates and joint ventures	1.1	3.0	3.4	3.9
Income (loss) from continuing operations	18.8	21.3	53.4	47.7
Discontinued Operations
Income (loss) on discontinued operations	0	(1.3)	0	(1.2)
Net income (loss)	18.8	20.0	53.4	46.5
Net income (loss) attributable to noncontrolling interests	0	(0.1)	(0.2)	(0.1)
Net income (loss) attributable to AMCOL shareholders	18.8	20.1	53.6	46.6
Weighted average number of common shares outstanding (in shares)	32,071,202	31,799,536	32,024,603	31,671,781
Weighted average common and common equivalent shares (in shares)	32,452,878	32,193,458	32,340,239	32,127,558
Amounts attributable to AMCOL shareholders
Income from continuing operations, net of tax	18.8	21.4	53.6	47.8
Discontinued operations, net of tax	0	(1.3)	0	(1.2)
Net income	$ 18.8	$ 20.1	$ 53.6	$ 46.6
Basic earnings (loss) per share (in dollars per share)
Continuing operations (in dollars per share)	$ 0.59	$ 0.67	$ 1.67	$ 1.51
Discontinued operations (in dollars per share)	$ 0	$ (0.04)	$ 0	$ (0.04)
Net income	$ 0.59	$ 0.63	$ 1.67	$ 1.47
Diluted earnings (loss) per share (in dollars per share)
Continuing operations (in dollars per share	$ 0.58	$ 0.66	$ 1.66	$ 1.49
Discontinued operations (in dollars per share)	$ 0	$ (0.04)	$ 0	$ (0.04)
Net income (in dollars per share)	$ 0.58	$ 0.62	$ 1.66	$ 1.45
Dividends declared per share (in dollars per share)	$ 0.20	$ 0.18	$ 0.56	$ 0.54