CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Re-measurement loss of insurance claims and policyholders’ benefits	$ (104)	$ (125)	$ (88)

Insurance Claims And Policyholders Benefits, Including Policyholders' Dividends, Remeasurement Impact

No definition available.

Name:	l_InsuranceClaimsAndPolicyholdersBenefitsIncludingPolicyholdersDividendsRemeasurementImpact
Namespace Prefix:	l_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration