Document And Entity Information - shares	6 Months Ended
	Oct. 31, 2016	Dec. 01, 2016
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)		39,191,171
Document Type	10-Q
Document Period End Date	Oct. 31, 2016
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Amendment Flag	false