Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Net income (loss)	$ 58,536	[1]	$ 28,483	[1]	$ 31,937	[1]
Other comprehensive income (loss) -
Pension adjustment	(13,502)	[1]	(401)	[1]	5,736	[1]
Tax benefit (expense)	4,985	[1]	160	[1]	(2,226)	[1]
Unrealized gain (loss) on interest rate swap agreement	(2,373)	[1]	(3,584)	[1]	2,915	[1]
Tax benefit (expense)	889	[1]	1,320	[1]	(1,136)	[1]
Unrealized gain (loss) on available-for-sale securities	(10,366)	[1]	(11,395)	[1]	24,265	[1]
Tax benefit (expense)	1,022	[1]	4,119	[1]	(5,141)	[1]
Foreign currency translation adjustment	(24,856)	[1]	7,458	[1]	12,796	[1]
Total other comprehensive income (loss)	(44,201)	[1]	(2,323)	[1]	37,209	[1]
Comprehensive income (loss)	14,335	[1]	26,160	[1]	69,146	[1]
AMCOL Shareholders [Member]
Net income (loss)	58,521	[1]	29,235	[1]	32,042	[1]
Other comprehensive income (loss) -
Pension adjustment	(13,502)	[1]	(401)	[1]	5,736	[1]
Tax benefit (expense)	4,985	[1]	160	[1]	(2,226)	[1]
Unrealized gain (loss) on interest rate swap agreement	(2,373)	[1]	(3,584)	[1]	2,915	[1]
Tax benefit (expense)	889	[1]	1,320	[1]	(1,136)	[1]
Unrealized gain (loss) on available-for-sale securities	(10,366)	[1]	(11,395)	[1]	24,265	[1]
Tax benefit (expense)	1,022	[1]	4,119	[1]	(5,141)	[1]
Foreign currency translation adjustment	(24,114)	[1]	6,518	[1]	12,423	[1]
Total other comprehensive income (loss)	(43,459)	[1]	(3,263)	[1]	36,836	[1]
Comprehensive income (loss)	15,062	[1]	25,972	[1]	68,878	[1]
Noncontrolling Interest [Member]
Net income (loss)	15	[1]	(752)	[1]	(105)	[1]
Other comprehensive income (loss) -
Pension adjustment	0	[1]	0	[1]	0	[1]
Tax benefit (expense)	0	[1]	0	[1]	0	[1]
Unrealized gain (loss) on interest rate swap agreement	0	[1]	0	[1]	0	[1]
Tax benefit (expense)	0	[1]	0	[1]	0	[1]
Unrealized gain (loss) on available-for-sale securities	0	[1]	0	[1]	0	[1]
Tax benefit (expense)	0	[1]	0	[1]	0	[1]
Foreign currency translation adjustment	(742)	[1]	940	[1]	373	[1]
Total other comprehensive income (loss)	(742)	[1]	940	[1]	373	[1]
Comprehensive income (loss)	$ (727)	[1]	$ 188	[1]	$ 268	[1]

[1] Restated