Senior and Subordinated Debt - Senior Debt (Detail) (USD $) In Thousands, unless otherwise specified				3 Months Ended		0 Months Ended	3 Months Ended		3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 25, 2012	Mar. 31, 2014 Lazard Group 6.85% Senior Notes [Member]	Dec. 31, 2013 Lazard Group 6.85% Senior Notes [Member]	Nov. 30, 2013 Lazard Group 4.25% Senior Notes [Member]	Mar. 31, 2014 Lazard Group 4.25% Senior Notes [Member]	Dec. 31, 2013 Lazard Group 4.25% Senior Notes [Member]	Mar. 31, 2014 Lazard Group Credit Facility [Member]
Debt Instrument [Line Items]
Senior Debt, Outstanding	$ 1,048,350	$ 1,048,350		$ 548,350	$ 548,350		$ 500,000	$ 500,000
Revolving Credit Facility, Initial Principal Amount			150,000						150,000
Senior Debt, Maturity Date				Jun. 15, 2017		Nov. 14, 2020	Nov. 14, 2020
Credit Facility, Expiration Date									Sep. 25, 2015
Revolving Credit Facility, Annual Interest Rate									0.78%
Senior Debt, Initial Principal Amount				$ 600,000		$ 500,000	$ 500,000
Senior Debt, Annual Interest Rate				6.85%		4.25%	4.25%