Document And Entity Information - shares	3 Months Ended
	Jul. 31, 2017	Aug. 31, 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)		37,897,078
Document Type	10-Q
Document Period End Date	Jul. 31, 2017
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Amendment Flag	false