Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Jan. 29, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	LAZ
Entity Registrant Name	LAZARD LTD
Entity Central Index Key	0001311370
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of each class	Class A Common Stock
Name of each exchange on which registered	NYSE
Entity File Number	001-32492
Entity Incorporation, State or Country Code	D0
Entity Tax Identification Number	98-0437848
Entity Common Stock, Shares Outstanding		112,766,091
Entity Public Float			$ 3,646,066,351
Document Annual Report	true
Document Transition Report	false
Entity Address, Address Line One	Clarendon House
Entity Address, Address Line Two	2 Church Street
Entity Address, City or Town	Hamilton
Entity Address, State or Province	HM11
Entity Address, Country	BM
City Area Code	441
Local Phone Number	295-1422
Documents Incorporated by Reference	Portions of the Registrant’s proxy statement for its 2020 annual general meeting of shareholders are incorporated by reference in this Form 10-K in response to Part III Items 10, 11, 12, 13 and 14.
Subsidiaries of Lazard Ltd [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		9,023,493