Basis of Presentation - Effects of Adoption of ASU 2018-12, Operations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Insurance claims and policyholders’ benefits	$ 1,653	$ 1,478
Income before income tax	519	439
Income tax expense	(115)	(87)
Net income	404	352
Amounts attributable to noncontrolling interests	(29)	(30)
Net income attributable to Loews Corporation	$ 375	$ 322
Basic net income per share (in dollars per share)	$ 1.61	$ 1.30
Diluted net income per share (in dollars per share)	$ 1.61	$ 1.29
Re-measurement gain of insurance claims and policyholders’ benefits	$ 1	$ 5
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Insurance claims and policyholders’ benefits		1,455
Income before income tax		462
Income tax expense		(92)
Net income		370
Amounts attributable to noncontrolling interests		(32)
Net income attributable to Loews Corporation		$ 338
Basic net income per share (in dollars per share)		$ 1.36
Diluted net income per share (in dollars per share)		$ 1.36
Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Insurance claims and policyholders’ benefits		$ 23
Income before income tax		(23)
Income tax expense		5
Net income		(18)
Amounts attributable to noncontrolling interests		2
Net income attributable to Loews Corporation		$ (16)
Basic net income per share (in dollars per share)		$ (0.06)
Diluted net income per share (in dollars per share)		$ (0.07)