Incentive Plans - Schedule of Issuance of RSUs and Charges to Retained Earnings (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of RSUs issued	115,297
Charges to retained earnings, net of estimated forfeitures	$ 5,013

Charge To Retained Earnings Pertaining To Issuance Of Restricted Stock Units In Connection With Participation Rights

No definition available.

Name:	laz_ChargeToRetainedEarningsPertainingToIssuanceOfRestrictedStockUnitsInConnectionWithParticipationRights
Namespace Prefix:	laz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration