Document and Entity Information - USD ($)	12 Months Ended
	Jul. 31, 2018	Aug. 31, 2018	Jan. 31, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jul. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	THO
Entity Registrant Name	THOR INDUSTRIES INC
Entity Central Index Key	0000730263
Current Fiscal Year End Date	--07-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		52,695,365
Entity Public Float			$ 6,895,000,000