Document And Entity Information - USD ($)	12 Months Ended
	Jul. 31, 2018	Sep. 14, 2018	Jan. 31, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	DONALDSON CO INC
Entity Central Index Key	0000029644
Current Fiscal Year End Date	--07-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Jul. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Common Stock, Shares Outstanding		128,068,092
Entity Public Float			$ 6,563,203,766