Restatement of Previously Issued Financial Statements - Reconciliation of Sales and Cost of Sales (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Sales	$ 110,223	$ 111,283	$ 103,477	$ 108,168	$ 99,096	$ 101,464	$ 89,066	$ 84,137	$ 433,151	$ 373,763	$ 294,517
Cost of sales	98,976	99,829	94,076	96,360	91,779	91,046	82,223	74,880	389,241	339,928	271,063
Industrial Ingredients [Member]
Sales									330,607	291,523	224,259
As Previously Reported [Member]
Sales	91,505	92,924	86,188	90,746	83,638	85,233	74,304	72,266	361,363	315,441	254,274
Cost of sales	80,258	81,470	76,787	78,938	76,321	74,815	67,461	63,009	317,453	281,606	230,820
As Previously Reported [Member] | Industrial Ingredients [Member]
Sales									258,819	233,201	184,016
Adjustment [Member]
Sales	18,718	18,359	17,289	17,422	15,458	16,231	14,762	11,871	71,788	58,322	40,243
Cost of sales	18,718	18,359	17,289	17,422	15,458	16,231	14,762	11,871	71,788	58,322	40,243
Adjustment [Member] | Industrial Ingredients [Member]
Sales									$ 71,788	$ 58,322	$ 40,243