Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Cover page.    
Document Quarterly Report true  
Document Transition Report false  
Security Exchange Name NYSE  
Title of 12(b) Security Common Shares, $1.00 Par Value  
City Area Code 440  
Entity Incorporation, State or Country Code OH  
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  
Entity File Number 001-09518  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   584,647,532
Trading Symbol PGR  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Tax Identification Number 34-0963169  
Entity Address, Address Line One 6300 Wilson Mills Road,  
Entity Address, City or Town Mayfield Village,  
Entity Address, State or Province OH  
Entity Address, Postal Zip Code 44143  
Local Phone Number 461-5000  
Entity Information, Former Legal or Registered Name Not Applicable  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Shell Company false