Condensed Consolidated Statements Of Comprehensive Income (Loss) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net income (loss)	$ 19,469	$ 17,307	$ 45,463	$ 39,372
Other comprehensive income (loss):
Foreign currency translation adjustment	(22,630)	18,508	(20,274)	5,606
Unrealized gain (loss) on available-for-sale securities, net of tax	(1,596)	(4,215)	(8,189)	(4,883)
Unrealized gain (loss) on interest rate swap agreements, net of tax	(1,302)	(1,288)	(1,652)	(3,662)
Pension adjustment, net of tax	25	30	75	94
Comprehensive income (loss)	(6,034)	30,342	15,423	36,527
AMCOL Shareholders [Member]
Net income (loss)	19,425	17,417	45,415	39,694
Other comprehensive income (loss):
Foreign currency translation adjustment	(21,982)	18,493	(19,627)	5,655
Unrealized gain (loss) on available-for-sale securities, net of tax	(1,596)	(4,215)	(8,189)	(4,883)
Unrealized gain (loss) on interest rate swap agreements, net of tax	(1,302)	(1,288)	(1,652)	(3,662)
Pension adjustment, net of tax	25	30	75	94
Comprehensive income (loss)	(5,430)	30,437	16,022	36,898
Noncontrolling Interest [Member]
Net income (loss)	44	(110)	48	(322)
Other comprehensive income (loss):
Foreign currency translation adjustment	(648)	15	(647)	(49)
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)	$ (604)	$ (95)	$ (599)	$ (371)