CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Continuing Operations
Net sales	$ 263.5	$ 249.2	$ 755.2	$ 731.8
Cost of sales	246.1	180.5	605.0	527.1
Gross profit	17.4	68.7	150.2	204.7
Selling, general and administrative expenses	42.0	40.3	133.6	124.9
Operating profit (loss)	(24.6)	28.4	16.6	79.8
Other income (expense):
Interest expense, net	(2.6)	(2.6)	(7.6)	(8.0)
Other, net	(0.8)	0	(2.0)	(2.7)
Total other income (expense), net	(3.4)	(2.6)	(9.6)	(10.7)
Income (loss) before income taxes and income from affiliates and joint ventures	(28.0)	25.8	7.0	69.1
Income tax expense (benefit)	(4.8)	7.6	5.0	19.2
Income (loss) before income from affiliates and joint ventures	(23.2)	18.2	2.0	49.9
Income from affiliates and joint ventures	0.7	1.0	2.5	3.4
Income (loss) from continuing operations	(22.5)	19.2	4.5	53.3
Discontinued Operations
Income (loss) on discontinued operations	(4.1)	(0.2)	(4.0)	0.6
Net income (loss)	(26.6)	19.0	0.5	53.9
Net income (loss) attributable to noncontrolling interests	(6.8)	0	(6.8)	(0.2)
Net income (loss) attributable to AMCOL shareholders	(19.8)	19.0	7.3	54.1
Weighted average common shares outstanding (in shares)	32,516,744	32,071,202	32,438,002	32,024,603
Weighted average common and common equivalent shares outstanding (in shares)	32,516,744	32,452,878	32,741,329	32,340,239
Amounts attributable to AMCOL shareholders
Income (loss) from continuing operations, net of tax	(15.7)	19.2	11.3	53.5
Discontinued operations, net of tax	(4.1)	(0.2)	(4.0)	0.6
Net income (loss)	$ (19.8)	$ 19.0	$ 7.3	$ 54.1
Basic earnings (loss) per share
Continuing operations (in dollars per share)	$ (0.48)	$ 0.60	$ 0.34	$ 1.67
Discontinued operations (in dollars per share)	$ (0.13)	$ (0.01)	$ (0.12)	$ 0.02
Net income (loss) (in dollars per share)	$ (0.61)	$ 0.59	$ 0.22	$ 1.69
Diluted earnings (loss) per share
Continuing operations (in dollars per share)	$ (0.48)	$ 0.60	$ 0.34	$ 1.65
Discontinued operations (in dollars per share)	$ (0.13)	$ (0.01)	$ (0.12)	$ 0.02
Net income (loss) (in dollars per share)	$ (0.61)	$ 0.59	$ 0.22	$ 1.67
Dividends declared per share (in dollars per share)	$ 0.20	$ 0.20	$ 0.60	$ 0.56