Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income (loss)	$ 21.3	$ 13.2	$ 34.6	$ 26.5
Other comprehensive income (loss):
Foreign currency translation adjustment	(14.3)	0.4	(3.5)	2.2
Unrealized gain (loss) on available-for-sale securities, net of tax	0.1	(3.7)	(0.8)	(6.6)
Unrealized gain (loss) on interest rate swap agreements, net of tax	(0.2)	(0.8)		(0.3)
Pension adjustment, net of tax	0.2		0.4
Comprehensive income (loss)	7.1	9.1	30.7	21.8
AMCOL Shareholders
Net income (loss)	21.6	13.2	34.8	26.5
Other comprehensive income (loss):
Foreign currency translation adjustment	(14.0)	0.4	(3.4)	2.2
Unrealized gain (loss) on available-for-sale securities, net of tax	0.1	(3.7)	(0.8)	(6.6)
Unrealized gain (loss) on interest rate swap agreements, net of tax	(0.2)	(0.8)		(0.3)
Pension adjustment, net of tax	0.2		0.4
Comprehensive income (loss)	7.7	9.1	31.0	21.8
Noncontrolling Interest
Net income (loss)	(0.3)		(0.2)
Other comprehensive income (loss):
Foreign currency translation adjustment	(0.3)		(0.1)
Unrealized gain (loss) on available-for-sale securities, net of tax
Unrealized gain (loss) on interest rate swap agreements, net of tax
Pension adjustment, net of tax
Comprehensive income (loss)	$ (0.6)		$ (0.3)