Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Jul. 26, 2019
Document and Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0000060086  
Current Fiscal Year End Date --12-31  
Document Period End Date Jun. 30, 2019  
Entity Registrant Name LOEWS CORP  
Entity Filer Category Large Accelerated Filer  
Trading Symbol L  
Entity Emerging Growth Company false  
Entity Small Business false  
Document Quarterly Report true  
Document Transition Report false  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 13-2646102  
Entity File Number 1-6541  
Entity Address, Address Line One 667 Madison Avenue  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10065-8087  
City Area Code 212  
Local Phone Number 521-2000  
Title of 12(b) Security Common stock  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Shell Company false  
Entity Address, City or Town NY  
Entity Common Stock, Shares Outstanding   302,380,038