Organization and Basis of Presentation - Additional Information (Detail) $ in Thousands		3 Months Ended
	Feb. 04, 2019	Mar. 31, 2021 USD ($) Segment	Dec. 31, 2020
Organization And Basis Of Presentation [Line Items]
Governing operating agreement, date	Feb. 04, 2019
Number of business segments | Segment		2
Lazard Group LLC [Member]
Organization And Basis Of Presentation [Line Items]
Percentage of common membership interests held		100.00%	100.00%
Lazard Growth Acquisition Corp I
Organization And Basis Of Presentation [Line Items]
LGAC IPO		$ 575,000
Redeemable noncontrolling interest,		575,000
Lazard Growth Acquisition Corp I | Net Underwriting Fee
Organization And Basis Of Presentation [Line Items]
Transaction costs associated with the IPO of special purpose entity		8,500
Lazard Growth Acquisition Corp I | Non-cash Deferred Underwriting Fees [Member]
Organization And Basis Of Presentation [Line Items]
Deferred costs associated with IPO of special purpose entity		20,125
Lazard Growth Acquisition Corp I | Other Offering Cost [Member]
Organization And Basis Of Presentation [Line Items]
Other offering costs associated with IPO of special purpose entity		$ 808