Organization and Basis of Presentation - Additional Information (Detail) (USD $)	3 Months Ended															3 Months Ended	12 Months Ended
	Mar. 31, 2014 Segment	Mar. 31, 2014 Class B Common Stock [Member]	Dec. 31, 2013 Class B Common Stock [Member]	Mar. 31, 2013 Class B Common Stock [Member]	Dec. 31, 2012 Class B Common Stock [Member]	Mar. 31, 2014 Class A Common Stock [Member]	Dec. 31, 2013 Class A Common Stock [Member]	Mar. 31, 2013 Class A Common Stock [Member]	Dec. 31, 2012 Class A Common Stock [Member]	Mar. 31, 2014 Lazard Ltd [Member]	Dec. 31, 2013 Lazard Ltd [Member]	Mar. 31, 2014 LAZ-MD Holdings LLC [Member]	Dec. 31, 2013 LAZ-MD Holdings LLC [Member]	Mar. 31, 2014 LAZ-MD Holdings LLC [Member] Class B Common Stock [Member]	Dec. 31, 2013 LAZ-MD Holdings LLC [Member] Class B Common Stock [Member]	Mar. 31, 2014 LAZ-MD Holdings LLC [Member] Class A Common Stock [Member]	Dec. 31, 2013 LAZ-MD Holdings LLC [Member] Class A Common Stock [Member]
Organization And Basis Of Presentation [Line Items]
Percentage of common membership interests held										99.50%	99.50%	0.50%	0.50%
Governing Operating Agreement, date	May 10, 2005
Common membership voting power held																0.60%	0.60%
Common stock, par value		$ 0.01	$ 0.01			$ 0.01	$ 0.01
Common stock, shares outstanding		1	1			129,056,081	129,056,081							1	1
Common stock, shares issued		1	1	1	1	129,056,081	129,056,081	128,216,423	128,216,423					1	1
Number of business segments	2