Document and Entity Information	6 Months Ended
	Jun. 30, 2018 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	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Trading Symbol	PGR
Entity Common Stock, Shares Outstanding	582,512,182