Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]		Additional Paid-In-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]	Class A Common Stock Held By Subsidiaries [Member]	Total Lazard Ltd Stockholders' Equity [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2016	$ 1,293,813	$ 1,298		$ 688,231	$ 1,134,186	$ (314,222)	$ (273,506)	$ 1,235,987	$ 57,826
Balance (in shares) at Dec. 31, 2016		129,766,091	[1]				7,628,786
Adjustment for the cumulative effect on prior years from the adoption of new accounting guidance related to share-based incentive compensation at Dec. 31, 2016	81,544				81,544			81,544
Balance, as adjusted at Dec. 31, 2016	1,375,357	$ 1,298		688,231	1,215,730	(314,222)	$ (273,506)	1,317,531	57,826
Comprehensive income (loss)
Net income	259,847				253,583			253,583	6,264
Other comprehensive income (loss) - net of tax	81,705					81,704		81,704	1
Amortization of share-based incentive compensation	272,965			272,965				272,965
Dividend equivalents	(5,908)			41,746	(47,654)			(5,908)
Class A common stock dividends	(341,450)				(341,450)			(341,450)
Purchase of Class A common stock	$ (306,741)						$ (306,741)	(306,741)
Purchase of Class A common stock (in shares)	(6,956,097)						6,956,097
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit (expense)	$ (73,170)			(213,978)			$ 140,808	(73,170)
Delivery of Class A common stock in connection with share-based incentive compensation and related tax expense (in shares)							(3,790,267)
Business acquisitions and related equity transactions:
Class A common stock issuable (including related amortization)	508			508				508
Delivery of Class A common stock and related tax benefit (expense)	577			(1,332)			$ 1,909	577
Delivery of Class A common stock and related tax benefit (in shares)							(47,474)
Distributions to noncontrolling interests, net	(5,193)								(5,193)
Other	408				204			204	204
Balance at Dec. 31, 2017	1,258,905	$ 1,298		788,140	1,080,413	(232,518)	$ (437,530)	1,199,803	59,102
Balance (in shares) at Dec. 31, 2017		129,766,091	[1]				10,747,142
Comprehensive income (loss)
Net income	532,449				527,125			527,125	5,324
Other comprehensive income (loss) - net of tax	(41,301)					(41,300)		(41,300)	(1)
Amortization of share-based incentive compensation	267,573			267,573				267,573
Dividend equivalents	(6,328)			44,255	(50,583)			(6,328)
Class A common stock dividends	(359,639)				(359,639)			(359,639)
Purchase of Class A common stock	$ (552,872)						$ (552,872)	(552,872)
Purchase of Class A common stock (in shares)	(12,206,652)						12,206,652
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit (expense)	$ (118,072)			(350,481)			$ 232,409	(118,072)
Delivery of Class A common stock in connection with share-based incentive compensation and related tax expense (in shares)							(5,353,920)
Business acquisitions and related equity transactions:
Class A common stock issuable (including related amortization)	561			561				561
Delivery of Class A common stock and related tax benefit (expense)				(1,109)			$ 1,109
Delivery of Class A common stock and related tax benefit (in shares)							(25,069)
Dividend-equivalents				1,753	(1,753)
Distributions to noncontrolling interests, net	(11,183)								(11,183)
Balance at Dec. 31, 2018	970,093	$ 1,298		750,692	1,195,563	(273,818)	$ (756,884)	916,851	53,242
Balance (in shares) at Dec. 31, 2018		129,766,091	[1]				17,574,805
Comprehensive income (loss)
Net income	297,716				286,500			286,500	11,216
Other comprehensive income (loss) - net of tax	(19,830)					(19,830)		(19,830)
Amortization of share-based incentive compensation	253,284			248,104				248,104	5,180
Dividend equivalents	(7,536)			28,801	(32,899)			(4,098)	(3,438)
Class A common stock dividends	(254,924)				(254,924)			(254,924)
Purchase of Class A common stock	$ (494,687)						$ (494,687)	(494,687)
Purchase of Class A common stock (in shares)	(13,674,439)						13,674,439
Cancellation of Class A common stock held		$ (170)		(675,911)			$ 676,081
Cancellation of Class A common stock held (in shares)		(17,000,000)	[1]				(17,000,000)
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit (expense)	$ (95,522)			(336,970)			$ 241,448	(95,522)
Delivery of Class A common stock in connection with share-based incentive compensation and related tax expense (in shares)							(5,686,227)
Business acquisitions and related equity transactions:
Class A common stock issuable (including related amortization)	27,592			27,592				27,592
Delivery of Class A common stock and related tax benefit (expense)	5			(1,958)			$ 1,963	5
Delivery of Class A common stock and related tax benefit (in shares)							(49,524)
Dividend-equivalents				670	(670)
Distributions to noncontrolling interests, net	(11,495)								(11,495)
Consolidation of VIEs	16,878								16,878
Balance at Dec. 31, 2019	$ 681,574	$ 1,128		$ 41,020	$ 1,193,570	$ (293,648)	$ (332,079)	$ 609,991	$ 71,583
Balance (in shares) at Dec. 31, 2019		112,766,091	[1]				8,513,493

[1] Includes 129,766,091 shares of the Company’s Class A common stock issued at both December 31, 2017 and 2018 and 112,766,091 shares of the Company’s Class A common stock issued at December 31, 2019.