Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Aug. 31, 2012
Nov. 05, 2012
Feb. 29, 2012
Document Document And Entity Information [Abstract]      
Document Type 10-K/A    
Amendment Flag true    
Amendment Description This Amendment No. 1 reflects a correction of an error in the presentation of the proceeds from the sale of by-products from the Company’s manufacturing operations as sales rather than a reduction of cost of sales in the Consolidated Statements of Operations. The Company has also corrected an error in the Consolidated Statements of Cash Flows to classify proceeds and payments related to a short term financing arrangement as a financing activity rather than as an operating activity.    
Document Period End Date Aug. 31, 2012    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY    
Trading Symbol PENX    
Entity Registrant Name PENFORD CORP    
Entity Central Index Key 0000739608    
Current Fiscal Year End Date --08-31    
Entity Well-known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   12,351,939  
Entity Public Float     $ 62.4