Document and Entity Information
 3 Months Ended
Nov. 30, 2012
Jan. 09, 2013
Document Document And Entity Information [Abstract]    
Document Type 10-Q/A  
Amendment Flag true  
Amendment Description This Amendment No. 1 reflects a correction in the presentation of the proceeds from the sale of by-products from the Company's manufacturing operations as sales rather than as a reduction of cost of sales in the Condensed 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 Nov. 30, 2012  
Document Fiscal Year Focus 2013  
Document Fiscal Period Focus Q1  
Trading Symbol PENX  
Entity Registrant Name PENFORD CORP  
Entity Central Index Key 0000739608  
Current Fiscal Year End Date --08-31  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   12,376,428