Goodwill and Other Intangible Assets - Estimated Future Amortization Expense (Parenthetical) (Detail)	3 Months Ended
Mar. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible asset amortization attributable to noncontrolling interest, percentage	43.00%

Percentage of Intangible asset amortization attributable to noncontrolling interest

No definition available.

Name:	laz_IntangibleAssetAmortizationAttributableToNoncontrollingInterestPercentage
Namespace Prefix:	laz_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration