Summary of Significant Accounting Policies, Future Policy Benefit Reserves (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, before Reinsurance [Abstract]
Premium deficiency		$ 72
Long term care active life reserves, weighted average interest rate	5.30%		5.40%

The interest-adjusted benefit ratio, which includes the change in active life reserves and investment income.

No definition available.

Name:	l_LongTermCareActiveLifeReservesInterestRate
Namespace Prefix:	l_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant