XML 30 R1.htm IDEA: XBRL DOCUMENT v3.8.0.1
Document And Entity Information - shares
 6 Months Ended
Oct. 31, 2017
Nov. 30, 2017
Document And Entity Information    
Entity Registrant Name Caseys General Stores Inc,  
Entity Central Index Key 0000726958  
Current Fiscal Year End Date --04-30  
Entity Filer Category Large Accelerated Filer  
Entity Current Reporting Status Yes  
Entity Voluntary Filers No  
Entity Well-known Seasoned Issuer No  
Entity Common Stock, Shares Outstanding (in shares)   37,547,264
Document Type 10-Q  
Document Period End Date Oct. 31, 2017  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q2  
Amendment Flag false