Document and Entity Information	9 Months Ended
	Sep. 30, 2017 shares
Document Document And Entity Information [Abstract]
Entity Registrant Name	PROGRESSIVE CORP/OH/
Entity Central Index Key	0000080661
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Trading Symbol	PGR
Entity Common Stock, Shares Outstanding	581,634,009