XML 46 R35.htm IDEA: XBRL DOCUMENT v3.8.0.1

Investments - Additional Information (Detail) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Net unrealized gains on investments included in "AOCI"	$ 1,200,000,000	$ 909,000,000
Additional other than temporary impairment losses	$ 0

X

- Definition

Additional Other Than Temporary Impairment Losses Investments Available For Sale Securities

+ References

No definition available.

+ Details

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

X

- Definition

Net Unrealized Gains On Investments Included In Accumulated Other Comprehensive Income

+ References

No definition available.

+ Details

Name:	l_NetUnrealizedGainsOnInvestmentsIncludedInAccumulatedOtherComprehensiveIncome
Namespace Prefix:	l_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration