CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Continuing Operations
Net sales	$ 236.7	$ 235.5
Cost of sales	173.6	170.8
Gross profit	63.1	64.7
Selling, general and administrative expenses	46.8	43.3
Operating profit	16.3	21.4
Other income (expense):
Interest expense, net	(2.5)	(2.7)
Other, net	(0.7)	(2.1)
Total other income (expense), net	(3.2)	(4.8)
Income before income taxes and income (loss) from affiliates and joint ventures	13.1	16.6
Income tax expense	3.6	4.4
Income before income (loss) from affiliates and joint ventures	9.5	12.2
Income (loss) from affiliates and joint ventures	0.9	1.3
Net income (loss)	10.4	13.5
Net income (loss) attributable to noncontrolling interests	(0.1)	0.1
Net income (loss) attributable to AMCOL shareholders	$ 10.5	$ 13.4
Weighted average common shares outstanding (in shares)	32,383,863	31,979,894
Weighted average common and common equivalent shares outstanding (in shares)	32,669,496	32,291,758
Earnings per share attributable to AMCOL shareholders:
Basic earnings per share (in dollars per share)	$ 0.32	$ 0.42
Diluted earnings per share (in dollars per share)	$ 0.32	$ 0.41
Dividends declared per share (in dollars per share)	$ 0.20	$ 0.18