Lazard Group Distributed Amounts to Subsidiaries of Lazard Ltd and LAZ-MD Holdings (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Schedule Of Group Distributions [Line Items]
Amounts distributed by Lazard Group	$ 69,948	$ 54,689
Subsidiaries Of Lazard Ltd [Member]
Schedule Of Group Distributions [Line Items]
Amounts distributed by Lazard Group	66,219	51,409
LAZ-MD Holdings [Member]
Schedule Of Group Distributions [Line Items]
Amounts distributed by Lazard Group	$ 3,729	$ 3,280