Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 05, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Registrant Name	LOEWS CORP
Entity Central Index Key	0000060086
Current Fiscal Year End Date	--12-31
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Document Transition Report	false
Entity File Number	1-06541
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-2646102
Entity Address, Address Line One	667 Madison Avenue
Entity Address, City or Town	New York
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, par value $0.01 per share
Trading Symbol	L
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 8,143,000,000
Entity Common Stock, Shares Outstanding		267,046,558