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