Document And Entity Information - shares	6 Months Ended
	Oct. 31, 2018	Nov. 27, 2018
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 Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding (in shares)		36,605,506
Document Type	10-Q
Document Period End Date	Oct. 31, 2018
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false