Summary of Significant Accounting Policies, Credit Losses (Details)	12 Months Ended
Dec. 31, 2020
Credit Losses [Abstract]
Period of time after interest becomes delinquent that asset is placed on nonaccrual status	90 days

Period of time after interest becomes delinquent that an asset is placed on nonaccrual status, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

Name:	l_PeriodOfTimeAfterInterestBecomesDelinquentThatAssetIsPlacedOnNonaccrualStatus
Namespace Prefix:	l_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration