Organization and Basis of Presentation - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended
	May 31, 2014	Mar. 31, 2015 Segment	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
Organization And Basis Of Presentation [Line Items]
Governing operating agreement, date		May 10, 2005
Common stock, Class B shares conversion to Class A shares	1
Common stock conversion basis	In May 2014, the remaining outstanding Lazard Group common membership interests held by LAZ-MD Holdings were exchanged for shares of the Company’s Class A common stock, and the sole issued and outstanding share of the Company’s Class B common stock was automatically converted into one share of the Company’s Class A common stock pursuant to the provisions of the Company’s bye-laws, resulting in only one outstanding class of common stock (the “Final Exchange of LAZ-MDInterests”). Following the Final Exchange of LAZ-MD Interests, Lazard Group became a wholly-owned indirect subsidiary of Lazard Ltd.
Number of business segments		2
Class B Common Stock [Member]
Organization And Basis Of Presentation [Line Items]
Common stock, shares issued			1	1
Class A Common Stock [Member]
Organization And Basis Of Presentation [Line Items]
Common stock, par value	0.01	0.01			$ 0.01
Common stock, shares outstanding		129,766,091			129,766,091
Common stock, shares issued		129,766,091	129,056,081	129,056,081	129,766,091
LAZ-MD Holdings LLC [Member] | Class B Common Stock [Member]
Organization And Basis Of Presentation [Line Items]
Common stock, shares outstanding				1
Common stock, shares issued				1
Lazard Group Llc [Member]
Organization And Basis Of Presentation [Line Items]
Percentage of common membership interests held		100.00%			100.00%
Lazard Group Llc [Member] | LAZ-MD Holdings LLC [Member]
Organization And Basis Of Presentation [Line Items]
Percentage of common membership interests held				0.50%