Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			3 Months Ended			1 Months Ended				3 Months Ended	1 Months Ended					3 Months Ended
	Mar. 31, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012 Lazard Ltd [Member]	Mar. 31, 2013 Series A Preferred Stock [Member]	Dec. 31, 2012 Series A Preferred Stock [Member]	Oct. 31, 2012 Class A Common stock [Member]	Apr. 30, 2012 Class A Common stock [Member]	Oct. 31, 2011 Class A Common stock [Member]	Feb. 28, 2011 Class A Common stock [Member]	Mar. 31, 2013 Class A Common stock [Member]	Apr. 25, 2013 Class A Common stock [Member] Subsequent event [Member]	Oct. 31, 2012 Share Repurchase Program [Member]	Apr. 30, 2012 Share Repurchase Program [Member]	Oct. 31, 2011 Share Repurchase Program [Member]	Feb. 28, 2011 Share Repurchase Program [Member]	Mar. 31, 2013 Share Repurchase Program [Member]
Schedule Of Stockholders Equity [Line Items]
Shares in exchange of a like number of common membership interests				85,196
Stock/membership interest repurchase program authorized amount													$ 200,000	$ 125,000	$ 125,000	$ 250,000
Share repurchase program expiration date							Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Number of shares/common membership interests purchased during current year											831,157
Aggregate cost of shares/common membership interests purchased											30,168
Share repurchase amount unused																	$ 123,898
Authorized shares of preferred stock		15,000,000	15,000,000
Par value of preferred stock		$ 0.01	$ 0.01
Outstanding shares of preferred stock					7,921	7,921
DIVIDENDS DECLARED PER SHARE OF COMMON STOCK	$ 0.16											$ 0.25
Dividend payable date												May 24, 2013
Dividend date of record												May 06, 2013
Dividend declare date												Apr. 25, 2013