CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Net income (loss)	$ 13.5	[1]	$ 13.1	[1]
Other comprehensive income (loss):
Foreign currency translation adjustment	10.7	[1]	1.8	[1]
Unrealized gain (loss) on available-for-sale securities, net of tax	(0.9)	[1]	(2.9)	[1]
Unrealized gain (loss) on interest rate swap agreements, net of tax	0.2	[1]	0.5	[1]
Pension adjustment, net of tax	0.2	[1]	0	[1]
Comprehensive income (loss)	23.7	[1]	12.5	[1]
AMCOL Shareholders
Net income (loss)	13.4	[1]	13.1	[1]
Other comprehensive income (loss):
Foreign currency translation adjustment	10.5	[1]	1.8	[1]
Unrealized gain (loss) on available-for-sale securities, net of tax	(0.9)	[1]	(2.9)	[1]
Unrealized gain (loss) on interest rate swap agreements, net of tax	0.2	[1]	0.5	[1]
Pension adjustment, net of tax	0.2	[1]	0	[1]
Comprehensive income (loss)	23.4	[1]	12.5	[1]
Noncontrolling Interest
Net income (loss)	0.1		0
Other comprehensive income (loss):
Foreign currency translation adjustment	0.2		0
Unrealized gain (loss) on available-for-sale securities, net of tax	0		0
Unrealized gain (loss) on interest rate swap agreements, net of tax	0		0
Pension adjustment, net of tax	0		0
Comprehensive income (loss)	$ 0.3		$ 0

[1] Restated