NONCONTROLLING INTEREST (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Change from net income and transfers from noncontrolling interest [Abstract]
Net income attributable to AMCOL shareholders	$ 13.4	[1]	$ 13.1	[1]
Transfers from noncontrolling interest [Abstract]
Decrease in additional paid-in capital for purchase of the remaining noncontrolling interest in Volclay South Africa (Proprietary) Limited			(5.7)
Decrease in additional paid-in capital for transfer of 26% interest in Batlhako			0
AMCOL Shareholders [Member]
Change from net income and transfers from noncontrolling interest [Abstract]
Net income attributable to AMCOL shareholders	13.4	[1]	13.1	[1]
Transfers from noncontrolling interest [Abstract]
Decrease in additional paid-in capital for purchase of the remaining noncontrolling interest in Volclay South Africa (Proprietary) Limited	0	[1]	(5.4)	[1]
Decrease in additional paid-in capital for transfer of 26% interest in Batlhako	0	[1]	(3.4)	[1]
Change from net income attributable to AMCOL shareholders and transfers from noncontrolling interest	$ 13.4	[1]	$ 4.3	[1]

[1] Restated