Lazard (LAZ) 10-Q 29 Oct 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 23, 2013	Oct. 23, 2013	Oct. 23, 2013
		Class A Common Stock [Member]	Subsidiaries of Lazard Ltd [Member]	Class B Common Stock [Member]
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	30-Sep-13
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
Trading Symbol	LAZ
Entity Registrant Name	LAZARD LTD
Entity Central Index Key	1311370
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		129,056,081	7,313,364	1

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Financial Condition (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS
Cash and cash equivalents	$688,367	$850,190
Deposits with banks	273,168	292,494
Cash deposited with clearing organizations and other segregated cash	59,541	65,232
Receivables (net of allowance for doubtful accounts of $26,160 and $23,017 at September 30, 2013 and December 31, 2012, respectively):
Fees	430,197	400,529
Customers and other	91,678	53,713
Related parties	14,276	23,801
Total receivables, net	536,151	478,043
Investments	469,722	414,673
Property (net of accumulated amortization and depreciation of $244,634 and $225,861 at September 30, 2013 and December 31, 2012, respectively)	249,780	225,033
Goodwill and other intangible assets (net of accumulated amortization of $38,039 and $35,281 at September 30, 2013 and December 31, 2012, respectively)	376,401	392,822
Other assets	303,326	268,406
Total Assets	2,956,456	2,986,893
Liabilities:
Deposits and other customer payables	289,872	269,763
Accrued compensation and benefits	382,064	467,578
Senior debt	1,076,850	1,076,850
Capital lease obligations	16,094	17,863
Related party payables	4,695	3,648
Other liabilities	529,820	499,651
Total Liabilities	2,299,395	2,335,353
Commitments and contingencies
Common stock:
Additional paid-in-capital	693,741	846,050
Retained earnings	219,319	182,647
Accumulated other comprehensive loss, net of tax	-127,852	-110,541
Stockholders' equity subtotal before common stock held by subsidiary and Noncontrolling interests, total	786,498	919,438
Total Lazard Ltd Stockholders' Equity	582,774	569,656
Noncontrolling interests	74,287	81,884
Total Stockholders' Equity	657,061	651,540
Total Liabilities and Stockholders' Equity	2,956,456	2,986,893
Series A Preferred Stock [Member]
Preferred stock, par value $.01 per share; 15,000,000 shares authorized:
Preferred stock
Series B Preferred Stock [Member]
Preferred stock, par value $.01 per share; 15,000,000 shares authorized:
Preferred stock
Class A Common Stock [Member]
Common stock:
Common stock	1,290	1,282
Class A common stock held by subsidiaries, at cost	-203,724	-349,782
Class B Common Stock [Member]
Common stock:
Common stock

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Financial Condition (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Allowance for doubtful accounts receivables	$26,160	$23,017
Property, accumulated amortization and depreciation	244,634	225,861
Intangible assets, accumulated amortization	$38,039	$35,281
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Series A Preferred Stock [Member]
Preferred stock, shares issued	7,921	7,921
Preferred stock, shares outstanding	7,921	7,921
Series B Preferred Stock [Member]
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A Common Stock [Member]
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	129,056,081	128,216,423
Common stock, shares outstanding	129,056,081	128,216,423
Common stock held by subsidiaries, shares	7,313,759	12,802,938
Class B Common Stock [Member]
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	1	1
Common stock, shares issued	1	1
Common stock, shares outstanding	1	1

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
REVENUE
Investment banking and other advisory fees	$232,006	$218,262	$660,351	$732,109
Money management fees	241,478	214,867	707,536	621,070
Interest income	1,347	733	3,823	4,598
Other	25,692	15,602	61,587	55,379
Total revenue	500,523	449,464	1,433,297	1,413,156
Interest expense	20,169	20,658	60,635	61,401
Net revenue	480,354	428,806	1,372,662	1,351,755
OPERATING EXPENSES
Compensation and benefits	301,809	283,818	910,679	905,527
Occupancy and equipment	27,393	25,680	96,435	80,309
Marketing and business development	17,077	19,096	60,646	69,685
Technology and information services	22,217	21,474	65,331	63,142
Professional services	12,904	8,514	32,223	31,099
Fund administration and outsourced services	14,475	13,179	43,328	39,300
Amortization of intangible assets related to acquisitions	877	2,494	2,758	6,172
Other	2,484	7,825	17,609	27,439
Total operating expenses	399,236	382,080	1,229,009	1,222,673
OPERATING INCOME	81,118	46,726	143,653	129,082
Provision for income taxes	18,370	13,053	31,335	32,191
NET INCOME	62,748	33,673	112,318	96,891
LESS - NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	2,466	372	5,323	7,217
NET INCOME ATTRIBUTABLE TO LAZARD LTD	$60,282	$33,301	$106,995	$89,674
WEIGHTED AVERAGE SHARES OF COMMON STOCK OUTSTANDING:
Basic	122,199,954	115,603,351	120,556,047	117,689,404
Diluted	134,242,144	135,380,036	133,174,000	135,537,050
NET INCOME PER SHARE OF COMMON STOCK:
Basic	$0.49	$0.29	$0.89	$0.76
Diluted	$0.45	$0.26	$0.81	$0.70
DIVIDENDS DECLARED PER SHARE OF COMMON STOCK	$0.25	$0.20	$0.50	$0.56

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
NET INCOME	$62,748	$33,673	$112,318	$96,891
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX:
Currency translation adjustments	12,157	14,306	-18,610	12,352
Amortization of interest rate hedge	264	264	791	791
Employee benefit plans:
Actuarial gain (loss) (net of tax (expense) benefit of $(25) and $994 for the three months ended September 30, 2013 and 2012, respectively, and $1,686 and $3,719 for the nine months ended September 30, 2013 and 2012, respectively)	50	-1,893	-2,669	-7,947
Adjustment for items reclassified to earnings (net of tax expense of $404 and $278 for the three months ended September 30, 2013 and 2012, respectively, and $1,206 and $856 for the nine months ended September 30, 2013 and 2012, respectively)	1,223	803	3,653	2,444
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	13,694	13,480	-16,835	7,640
COMPREHENSIVE INCOME	76,442	47,153	95,483	104,531
LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	2,523	1,086	5,201	7,784
COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD LTD	$73,919	$46,067	$90,282	$96,747

Condensed_Consolidated_Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Tax benefit (expense) on actuarial loss, employee benefit plans	($25)	$994	$1,686	$3,719
Tax expense, adjustment for items reclassified to earnings, employee benefit plans	$404	$278	$1,206	$856

Condensed_Consolidated_Stateme5

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
NET INCOME	$112,318	$96,891
Noncash items included in net income:
Depreciation and amortization of property	25,465	22,472
Amortization of deferred expenses, share-based incentive compensation and interest rate hedge	239,357	252,812
Amortization of intangible assets related to acquisitions	2,758	6,172
(Increase) decrease in operating assets:
Deposits with banks	25,558	18,465
Cash deposited with clearing organizations and other segregated cash	6,291	13,614
Receivables-net	-55,516	23,115
Investments	-54,520	-55,135
Other assets	-81,898	-54,449
Increase (decrease) in operating liabilities:
Deposits and other payables	14,158	-28,361
Accrued compensation and benefits and other liabilities	-66,104	-55,770
Net cash provided by operating activities	167,867	239,826
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property	-54,344	-71,722
Disposals of property	5,843	2,158
Net cash used in investing activities	-48,501	-69,564
Proceeds from:
Contribution from noncontrolling interests	805	1,544
Excess tax benefits from share-based incentive compensation	2,211
Payments for:
Capital lease obligations	-2,092	-1,878
Distributions to noncontrolling interests	-10,228	-17,399
Purchase of Class A common stock	-77,934	-222,679
Class A common stock dividends	-60,931	-66,219
Settlement of vested share-based incentive compensation	-125,546	-40,686
Other financing activities	-165	-99
Net cash used in financing activities	-273,880	-347,416
EFFECT OF EXCHANGE RATE CHANGES ON CASH	-7,309	6,303
NET DECREASE IN CASH AND CASH EQUIVALENTS	-161,823	-170,851
CASH AND CASH EQUIVALENTS-January 1	850,190	1,003,791
CASH AND CASH EQUIVALENTS-September 30	$688,367	$832,940

Condensed_Consolidated_Stateme6

Condensed Consolidated Statements of Changes in Stockholders' Equity (USD $)		Total	Series A Preferred Stock [Member]	Common Stock [Member]		Additional Paid-In-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]	Class A Common Stock Held By Subsidiaries [Member]	Total Lazard Ltd Stockholders' Equity [Member]	Noncontrolling Interests [Member]
In Thousands, except Share data, unless otherwise specified		USD ($)		USD ($)		USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)
Balance at Dec. 31, 2011		$866,856		$1,230		$659,013	$258,646	($88,364)	($104,382)	$726,143	$140,713
Balance (in shares) at Dec. 31, 2011			7,921	123,009,312	[1]				3,492,017
Comprehensive income (loss):
NET INCOME		96,891					89,674			89,674	7,217
Other comprehensive income (loss) - net of tax:
Currency translation adjustments		12,352						11,547		11,547	805
Amortization of interest rate hedge		791						751		751	40
Employee benefit plans:
Net actuarial loss		-7,947						-7,545		-7,545	-402
Adjustments for items reclassified to earnings		2,444						2,320		2,320	124
COMPREHENSIVE INCOME		104,531								96,747	7,784
Business acquisitions and related equity transactions:
Class A common stock issuable (including related amortization)		3,549				3,369				3,369	180
Amortization of share-based incentive compensation		220,175				209,036				209,036	11,139
Dividend-equivalents		-91				11,770	-11,856			-86	-5
Class A common stock dividends		-66,219					-66,219			-66,219
Purchase of Class A common stock		-222,679							-222,679	-222,679
Purchase of Class A common stock (in shares)									8,235,306
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit and tax expense		-41,658				-141,781			100,172	-41,609	-49
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit and tax expense (in shares)									-3,196,018
Class A common stock issued in exchange for Lazard Group common membership interests				2		-2
Class A common stock issued in exchange for Lazard Group common membership interests (in shares)	[1]			191,701
Distributions to noncontrolling interests, net		-15,855									-15,855
Deconsolidation of investment companies		-14,783									-14,783
Adjustments related to noncontrolling interests						9,242		-117		9,125	-9,125
Balance at Sep. 30, 2012		833,826		1,232		750,647	270,245	-81,408	-226,889	713,827	119,999
Balance (in shares) at Sep. 30, 2012			7,921	123,201,013	[1]				8,531,305
Balance at Dec. 31, 2012		651,540		1,282		846,050	182,647	-110,541	-349,782	569,656	81,884
Balance (in shares) at Dec. 31, 2012			7,921	128,216,424	[2]				12,802,938
Comprehensive income (loss):
NET INCOME		112,318					106,995			106,995	5,323
Other comprehensive income (loss) - net of tax:
Currency translation adjustments		-18,610						-18,478		-18,478	-132
Amortization of interest rate hedge		791						786		786	5
Employee benefit plans:
Net actuarial loss		-2,669						-2,654		-2,654	-15
Adjustments for items reclassified to earnings		3,653						3,633		3,633	20
COMPREHENSIVE INCOME		95,483								90,282	5,201
Business acquisitions and related equity transactions:
Class A common stock issuable (including related amortization)		834				829				829	5
Delivery of Class A common stock (including dividend-equivalents)						-4,994	-179		5,173
Delivery of Class A common stock, shares									-170,988
Amortization of share-based incentive compensation		183,341				182,338				182,338	1,003
Dividend-equivalents		-165				8,440	-8,604			-164	-1
Class A common stock dividends		-60,931					-60,931			-60,931
Purchase of Class A common stock		-77,934							-77,934	-77,934
Purchase of Class A common stock (in shares)									2,201,657
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit and tax expense		-124,684				-342,898	-609		218,819	-124,688	4
Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefit and tax expense (in shares)									-7,519,848
Class A common stock issued in exchange for Lazard Group common membership interests				8		-8
Class A common stock issued in exchange for Lazard Group common membership interests (in shares)	[2]			839,658
Distributions to noncontrolling interests, net		-9,423									-9,423
Adjustments related to noncontrolling interests		-1,000				3,984		-598		3,386	-4,386
Balance at Sep. 30, 2013		$657,061		$1,290		$693,741	$219,319	($127,852)	($203,724)	$582,774	$74,287
Balance (in shares) at Sep. 30, 2013			7,921	129,056,082	[2]				7,313,759
[1]	Includes 123,009,311 and 123,201,012 shares of the Company's Class A common stock issued at January 1, 2012 and September 30, 2012, respectively, and 1 share of the Company's Class B common stock issued at each such date.
[2]	Includes 128,216,423 and 129,056,081 shares of the Company's Class A common stock issued at January 1, 2013 and September 30, 2013, respectively, and 1 share of the Company's Class B common stock issued at each such date.

Condensed_Consolidated_Stateme7

Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
			Class A Common Stock [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]	Class B Common Stock [Member]	Class B Common Stock [Member]	Class B Common Stock [Member]	Class B Common Stock [Member]
Tax benefit or expenses related to delivery of Class A Common Stock in connection with share-based incentive compensation	$862	$972
Common stock, issued			129,056,081	128,216,423	123,201,012	123,009,311	1	1	1	1

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]
Organization and Basis of Presentation	1	ORGANIZATION AND BASIS OF PRESENTATION
	Organization
	Lazard Ltd, a Bermuda holding company, and its subsidiaries (collectively referred to as “Lazard Ltd”, “Lazard”, “we” or the “Company”), including Lazard Ltd’s indirect investment in Lazard Group LLC, a Delaware limited liability company (collectively referred to, together with its subsidiaries, as “Lazard Group”), is one of the world’s preeminent financial advisory and asset management firms and has long specialized in crafting solutions to the complex financial and strategic challenges of our clients. We serve a diverse set of clients around the world, including corporations, governments, institutions, partnerships and individuals.
	Lazard Ltd indirectly held approximately 99.5% and 98.8% of all outstanding Lazard Group common membership interests as of September 30, 2013 and December 31, 2012, respectively. Lazard Ltd, through its control of the managing members of Lazard Group, controls Lazard Group, which is governed by an Operating Agreement dated as of May 10, 2005, as amended (the “Operating Agreement”). LAZ-MD Holdings LLC (“LAZ-MD Holdings”), an entity owned by Lazard Group’s current and former managing directors, held approximately 0.5% and 1.2% of the outstanding Lazard Group common membership interests as of September 30, 2013 and December 31, 2012, respectively. Additionally, LAZ-MD Holdings was the sole owner of the one issued and outstanding share of Lazard Ltd’s Class B common stock (the “Class B common stock”) which provided LAZ-MD Holdings with approximately 0.5% and 1.2% of the voting power but no economic rights in the Company as of September 30, 2013 and December 31, 2012, respectively. Subject to certain limitations, LAZ-MD Holdings’ interests in Lazard Group are exchangeable for Lazard Ltd Class A common stock, par value $0.01 per share (“Class A common stock”).
	Our sole operating asset is our indirect ownership of common membership interests of Lazard Group and our managing member interest of Lazard Group, whose principal operating activities are included in two business segments:
		•	Financial Advisory, which offers corporate, partnership, institutional, government, sovereign and individual clients across the globe a wide array of financial advisory services regarding mergers and acquisitions (“M&A”) and other strategic matters, restructurings, capital structure, capital raising and various other financial matters, and
		•	Asset Management, which offers a broad range of global investment solutions and investment management services in equity and fixed income strategies, alternative investments and private equity funds to corporations, public funds, sovereign entities, endowments and foundations, labor funds, financial intermediaries and private clients.
	In addition, we record selected other activities in our Corporate segment, including management of cash, investments and outstanding indebtedness, as well as certain commercial banking activities of Lazard Group’s Paris-based subsidiary, Lazard Frères Banque SA (“LFB”).
	LFB is a registered bank regulated by the Autorité de Contrôle Prudentiel et de Résolution (“ACPR”). It is engaged primarily in commercial and private banking services for clients and funds managed by Lazard Frères Gestion SAS (“LFG”) and other clients, investment banking activities, including participation in underwritten offerings of securities in France, and asset-liability management.
	Basis of Presentation
	The accompanying condensed consolidated financial statements of Lazard Ltd have been prepared pursuant to the rules and regulations of the United States Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Accordingly, they do not include all of the information and notes required by accounting principles generally accepted in the United States of America (“U.S. GAAP”) for complete financial statements and should be read in conjunction with the audited consolidated financial statements and notes thereto included in Lazard Ltd’s Annual Report on Form 10-K for the year ended December 31, 2012 (the “Form 10-K”). The accompanying December 31, 2012 unaudited condensed consolidated statement of financial condition data was derived from audited consolidated financial statements, but does not include all disclosures required by U.S. GAAP for annual financial statement purposes. The accompanying condensed consolidated financial statements reflect all adjustments which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods presented.
	Preparing financial statements requires management to make estimates and assumptions that affect the amounts that are reported in the financial statements and the accompanying disclosures. Discretionary compensation and benefits expense for interim periods is accrued based on the year-to-date amount of revenue earned, and an assumed annual ratio of compensation and benefits expense to revenue, with the applicable amounts adjusted for certain items. Although these estimates are based on management’s knowledge of current events and actions that Lazard may undertake in the future, actual results may differ materially from the estimates.
	The consolidated results of operations for the three month and nine month periods ended September 30, 2013 are not necessarily indicative of the results to be expected for any future interim or annual period.
	The condensed consolidated financial statements include Lazard Ltd, Lazard Group and Lazard Group’s principal operating subsidiaries: Lazard Frères & Co. LLC (“LFNY”), a New York limited liability company, along with its subsidiaries, including Lazard Asset Management LLC and its subsidiaries (collectively referred to as “LAM”); the French limited liability companies Compagnie Financière Lazard Frères SAS (“CFLF”) along with its subsidiaries, LFB and LFG, and Maison Lazard SAS and its subsidiaries; and Lazard & Co., Limited (“LCL”), through Lazard & Co., Holdings Limited (“LCH”), an English private limited company, together with their jointly owned affiliates and subsidiaries.
	The Company’s policy is to consolidate (i) entities in which it has a controlling financial interest, (ii) variable interest entities (“VIEs”) where the Company has a variable interest and is deemed to be the primary beneficiary and (iii) limited partnerships where the Company is the general partner, unless the presumption of control is overcome. When the Company does not have a controlling interest in an entity, but exerts significant influence over such entity’s operating and financial decisions, the Company applies the equity method of accounting in which it records in earnings its share of earnings or losses of the entity. Intercompany transactions and balances have been eliminated.

Recent_Accounting_Developments

Recent Accounting Developments	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]
Recent Accounting Developments	2	RECENT ACCOUNTING DEVELOPMENTS
	Offsetting (Netting) Assets and Liabilities—In the first quarter of 2013, the Company adopted the new disclosure requirements issued by the Financial Accounting Standards Board (the “FASB”) regarding the nature of an entity’s rights of setoff and related arrangements associated with its financial instruments, including derivatives, repurchase agreements and reverse repurchase agreements and securities borrowing and securities lending transactions that are either (i) offset or (ii) subject to an enforceable master netting arrangement. The new disclosures are designed to make financial statements prepared under U.S. GAAP more comparable to those prepared under International Financial Reporting Standards (“IFRS”) and will enable users of an entity’s financial statements to evaluate the effect or potential effect of netting arrangements on an entity’s financial position. The disclosure requirements are effective for interim and annual reporting periods beginning on or after January 1, 2013, with retrospective application required. The adoption of the new disclosure requirements did not have a material impact on the Company’s consolidated financial statements.
	Reclassifications Out of Accumulated Other Comprehensive Income—In the first quarter of 2013, the Company adopted the FASB’s amended guidance regarding the presentation of amounts reclassified out of accumulated other comprehensive income. The amendment required that the amounts reclassified out of accumulated other comprehensive income be presented by component and disclosed where the respective line item was reported in the consolidated statement of operations. The amendment was to be applied prospectively, and is effective with interim and annual periods beginning after December 15, 2012, with early adoption permitted. The adoption of the amended guidance did not have a material impact on the Company’s consolidated financial statements.
	Presentation of Unrecognized Tax Benefits—In July 2013, the FASB issued guidance on the presentation of unrecognized tax benefits when net operating losses or tax credit carryforwards exist. The guidance requires that the unrecognized tax benefit, or a portion of such unrecognized tax benefit, be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except in certain situations, as defined in the guidance. The new presentation requirements are effective prospectively for interim and annual reporting periods beginning after December 15, 2013. The Company is currently evaluating this guidance, but does not anticipate its adoption will have a material impact on the Company’s consolidated financial statements.

Receivables

Receivables	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]
Receivables	3	RECEIVABLES
	The Company’s receivables represent receivables from fees, customers and other and related parties.
	Receivables are stated net of an estimated allowance for doubtful accounts of $26,160 and $23,017 at September 30, 2013 and December 31, 2012, respectively, for past due amounts and for specific accounts deemed uncollectible, which may include situations where a fee is in dispute. The Company recorded bad debt expense (recoveries) of $(198) and $1,644 for the three month and nine month periods ended September 30, 2013, respectively, and $1,553 and $2,701 for the three month and nine month periods ended September 30, 2012, respectively. In addition, the Company recorded charge-offs, foreign currency translation and other adjustments, which resulted in a net increase to the allowance for doubtful accounts of $1,765 and $1,499 for the three month and nine month periods ended September 30, 2013, respectively, and $15 and $173 for the three month and nine month periods ended September 30, 2012, respectively. At September 30, 2013 and December 31, 2012, the Company had receivables past due or deemed uncollectible of $36,255 and $25,604, respectively.
	Of the Company’s total receivables at September 30, 2013 and December 31, 2012, $58,531 and $76,481, respectively, represented interest-bearing financing fee receivables. Based upon our historical loss experience, the credit quality of the counterparties, and the lack of past due or uncollectible amounts, there was no allowance for doubtful accounts required at those dates related to such receivables.
	The aggregate carrying amount of our non-interest bearing receivables of $477,620 and $401,562 at September 30, 2013 and December 31, 2012, respectively, approximates fair value.

Investments

Investments	9 Months Ended
	Sep. 30, 2013
Investments Schedule [Abstract]
Investments	4	INVESTMENTS
	The Company’s investments and securities sold, not yet purchased, consisted of the following at September 30, 2013 and December 31, 2012:
			September 30,		December 31,
			2013		2012
	Debt (including interest-bearing deposits of $519 and $578, respectively)		$	7,501	$	5,948
	Equities			55,467		44,992
	Funds:
	Alternative investments (a)			45,809		57,890
	Debt (a)			58,605		32,077
	Equity (a)			177,831		154,310
	Private equity			115,568		112,444
				397,813		356,721
	Equity method			8,941		7,012
	Total investments			469,722		414,673
	Less:
	Interest-bearing deposits			519		578
	Equity method			8,941		7,012
	Investments, at fair value		$	460,262	$	407,083
	Securities sold, not yet purchased, at fair value (included in “other liabilities”)		$	4,075	$	2,755
	(a)	Interests in alternative investment funds, debt funds and equity funds include investments with fair values of $7,886, $31,029 and $125,571, respectively, at September 30, 2013 and $5,054, $18,615 and $76,907, respectively, at December 31, 2012, held in order to satisfy the Company’s liability upon vesting of previously granted Lazard Fund Interests (“Lazard Fund Interests”) and other similar deferred compensation arrangements. Lazard Fund Interests represent grants by the Company to eligible employees of actual or notional interests in a number of Lazard-managed funds (see Notes 6 and 12 of Notes to Condensed Consolidated Financial Statements).
	Debt securities primarily consist of seed investments invested in debt securities held within separately managed accounts related to our Asset Management business and non-U.S. government debt securities.
	Equities primarily consist of seed investments invested in marketable equity securities of large-, mid- and small-cap domestic, international and global companies held within separately managed accounts related to our Asset Management business.
	Interests in alternative investment funds primarily consist of interests in various Lazard-managed hedge funds and funds of funds.
	Debt funds primarily consist of seed investments in funds related to our Asset Management business, which invest in debt securities, and amounts related to Lazard Fund Interests discussed above.
	Equity funds primarily consist of seed investments in funds related to our Asset Management business, which are invested in equity securities, and amounts related to Lazard Fund Interests discussed above.
	Private equity investments include those owned by Lazard and those consolidated but not owned by Lazard. Private equity investments owned by Lazard are primarily comprised of investments in private equity funds. Such investments primarily include (i) a mezzanine fund, which invests in mezzanine debt of a diversified selection of small- to mid-cap European companies, (ii) a fund targeting significant noncontrolling-stake investments in established private companies, (iii) Edgewater Growth Capital Partners III, L.P. (“EGCP III”), a fund primarily making equity and buyout investments in middle market companies and (iv) Lazard Australia Corporate Opportunities Fund 2 (“COF2”), a Lazard-managed Australian fund targeting Australasian mid-market investments.
	Private equity investments consolidated but not owned by Lazard relate to the economic interests that are owned by the management team and other investors in the Edgewater Funds (“Edgewater”) which totaled $12,379 and $11,490 at September 30, 2013 and December 31, 2012, respectively (see Note 10 of Notes to Condensed Consolidated Financial Statements).
	During the three month and nine month periods ended September 30, 2013 and 2012, the Company reported in revenue-other on its condensed consolidated statements of operations gross unrealized investment gains and losses pertaining to “trading” securities as follows (including, for the three month and nine month periods ended September 30, 2012, restated amounts pertaining to certain non-broker dealer subsidiaries):
			Three Month Period				Nine Month Period
			Ended September 30,				Ended September 30,
			2013		2012		2013		2012
	Gross unrealized investment gains		$	10,925	$	11,825	$	12,044	$	19,137
	Gross unrealized investment losses		$	–	$	–	$	3,907	$	35

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Fair Value Measurements	5	FAIR VALUE MEASUREMENTS
	Lazard categorizes its investments and certain other assets and liabilities recorded at fair value into a three-level fair value hierarchy as follows:
	Level 1.	Assets and liabilities whose values are based on unadjusted quoted prices for identical assets or liabilities in an active market that Lazard has the ability to access.
	Level 2.	Assets and liabilities whose values are based on (i) quoted prices for similar assets or liabilities in an active market, or quoted prices for identical or similar assets or liabilities in non-active markets, (ii) assets valued based on net asset value (“NAV”) or its equivalent redeemable at the measurement date or within the near term without redemption restrictions, or (iii) inputs other than quoted prices that are directly observable or derived principally from, or corroborated by, market data.
	Level 3.	Assets and liabilities whose values are based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect our own assumptions about the assumptions a market participant would use in pricing the asset or liability. Items included in Level 3 include securities or other financial assets whose trading volume and level of activity have significantly decreased when compared with normal market activity and there is no longer sufficient frequency or volume to provide pricing information on an ongoing basis, as well as assets valued based on NAV or its equivalent, but not redeemable within the near term as a result of redemption restrictions.
	The Company’s investments in non-U.S. Government and other debt securities are classified as Level 1 when their respective fair values are based on unadjusted quoted prices in active markets and are classified as Level 2 when their fair values are primarily based on prices as provided by external pricing services.
	The fair value of equities is classified as Level 1 or Level 3 as follows: marketable equity securities are classified as Level 1 and are valued based on the last trade price on the primary exchange for that security as provided by external pricing services; equity securities in private companies are generally classified as Level 3.
	The fair value of investments in alternative investment funds is classified as either Level 2 or Level 3 depending on the time frame of any applicable redemption restriction, and is valued at NAV or its equivalent, which is primarily determined based on information provided by external fund administrators.
	The fair value of investments in debt funds is classified as Level 1 when the fair values are primarily based on the reported closing price for the fund, and classified as Level 2 when the fair values are primarily based on NAV or its equivalent and are redeemable within the near term.
	The fair value of investments in equity funds is classified as Level 1, 2 or 3 as follows: publicly traded asset management funds are classified as Level 1 and are valued based on the reported closing price for the fund; investments in asset management funds redeemable in the near term are classified as Level 2 and are valued at NAV or its equivalent, which is primarily determined based on information provided by external fund administrators; and funds valued based on NAV or its equivalent that are not redeemable within the near term are classified as Level 3.
	The fair value of investments in private equity funds is classified as Level 3, and is primarily based on NAV or its equivalent. Such investments are not redeemable within the near term.
	The fair values of derivatives entered into by the Company are classified as Level 2 and are based on the values of the related underlying assets, indices or reference rates as follows - the fair value of forward foreign currency exchange rate contracts is a function of the spot rate and the interest rate differential of the two currencies from the trade date to settlement date; the fair value of equity and fixed income swaps is based on the change in fair values of the related underlying equity security, financial instrument or index and a specified notional holding; the fair value of interest rate swaps is based on the interest rate yield curve; and the fair value of derivative liabilities related to Lazard Fund Interests and other similar deferred compensation arrangements is based on the value of the underlying investments, adjusted for forfeitures. See Note 6 of Notes to Condensed Consolidated Financial Statements.
	Where reported information regarding an investment is based on data received from external fund administrators or pricing services, the Company reviews such information and classifies the investment at the relevant level within the fair value hierarchy.
	The following tables present the classification of investments and certain other assets and liabilities measured at fair value on a recurring basis as of September 30, 2013 and December 31, 2012 within the fair value hierarchy:
			30-Sep-13
			Level 1		Level 2			Level 3			Total
	Assets:
	Investments:
	Debt (excluding interest-bearing deposits)		$	1,090	$	5,892		$	–		$	6,982
	Equities			54,144		–			1,323			55,467
	Funds:
	Alternative investments			–		45,809			–			45,809
	Debt			58,601		4			–			58,605
	Equity			177,792		39			–			177,831
	Private equity			–		–			115,568			115,568
	Derivatives			–		313			–			313
	Total		$	291,627	$	52,057		$	116,891		$	460,575
	Liabilities:
	Securities sold, not yet purchased		$	4,075	$	–		$	–		$	4,075
	Derivatives			–		159,267			–			159,267
	Total		$	4,075	$	159,267		$	–		$	163,342
			31-Dec-12
			Level 1		Level 2			Level 3			Total
	Assets:
	Investments:
	Debt (excluding interest-bearing deposits)		$	1,443	$	3,927		$	–		$	5,370
	Equities			44,802		–			190			44,992
	Funds:
	Alternative investments			–		54,433			3,457			57,890
	Debt			32,073		4			–			32,077
	Equity			145,231		9,069			10			154,310
	Private equity			–		–			112,444			112,444
	Derivatives			–		933			–			933
	Total		$	223,549	$	68,366		$	116,101		$	408,016
	Liabilities:
	Securities sold, not yet purchased		$	2,696	$	59		$	–		$	2,755
	Derivatives			–		102,492			–			102,492
	Total		$	2,696	$	102,551		$	–		$	105,247
	There were no transfers between any of the Level 1, 2 and 3 categories in the fair value measurement hierarchy during the three month and nine month periods ended September 30, 2013 and 2012.
	The following tables provide a summary of changes in fair value of the Company’s Level 3 assets for the three month and nine month periods ended September 30, 2013 and 2012:
			Three Months Ended September 30, 2013
			Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
			Balance		Realized			Acquisitions			Dispositions			Currency			Balance
					Gains (Losses)									Translation
					Included									Adjustments
					In Revenue-
					Other (a)
	Investments:
	Equities		$	637	$	2		$	650		$	–		$	34		$	1,323
	Alternative investment funds			11		(11	)		–			–			–			–
	Private equity funds			112,833		5,174			2,907			-6,848			1,502			115,568
	Total Level 3 Assets		$	113,481	$	5,165		$	3,557		$	-6,848		$	1,536		$	116,891
			Nine Months Ended September 30, 2013
			Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
Balance			Realized		Acquisitions			Dispositions			Currency			Balance
			Gains (Losses)								Translation
			Included								Adjustments
			In Revenue-
			Other (a)
Investments:
Equities		$	190	$	8		$	1,095		$	–			$  30		$	1,323
Alternative investment funds			3,457		117			–			(3,574	)		–			–
Equity funds			10		–			–			(10	)		–			–
Private equity funds			112,444		8,912			6,166			(12,716	)		762			115,568
Total Level 3 Assets		$	116,101	$	9,037		$	7,261		$	(16,300	)		$792		$	116,891
		Three Months Ended September 30, 2012
		Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
		Balance		Realized			Acquisitions			Dispositions			Currency			Balance
				Gains (Losses)									Translation
				Included									Adjustments
				In Revenue-
				Other (a)
Investments:
Equities		$	181	$	–		$	–		$	–		$	5		$	186
Alternative investment funds			4,626		18			10			(1,209	)		–			3,445
Private equity funds			113,991		(522	)		2,945			(348	)		1,128			117,194
Total Level 3 Assets		$	118,798	$	(504	)	$	2,955		$	(1,557	)	$	1,133		$	120,825
		Nine Months Ended September 30, 2012
		Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
		Balance		Realized			Acquisitions			Dispositions			Currency			Balance
				Gains (Losses)									Translation
				Included									Adjustments
				In Revenue-
				Other (a)
Investments:
Equities		$	211	$	5		$	–		$	(30	)	$	–		$	186
Alternative investment funds			10,171		107			20			(6,853	)		–			3,445
Private equity funds			122,718		11,828			5,697			(23,093	)		44			117,194
Total Level 3 Assets		$	133,100	$	11,940		$	5,717		$	(29,976	)	$	44		$	120,825
(a)	Earnings for the three month and nine month periods ended September 30, 2013 and the three month and nine month periods ended September 30, 2012 include net unrealized gains (losses) of $2,680, $6,007, $(460) and $9,103, respectively.
Fair Value of Certain Investments Based on NAV—The Company’s Level 2 and Level 3 investments at September 30, 2013 and December 31, 2012 include certain investments that are valued using NAV or its equivalent as a practical expedient in determining fair value. Information with respect thereto was as follows:
		30-Sep-13
							% of		Estimated Liquidation Period of				Investments Redeemable
							Fair Value		Investments Not Redeemable
							Not
		Fair Value		Unfunded			Redeemable		%	%		%	Redemption		Redemption
				Commitments					Next	10-May		Thereafter	Frequency		Notice Period
									5 Years	Years
Alternative investment funds		$	45,809	$	–		NA		NA	NA		NA	(a)		<30-90 days
Debt funds			4		–		NA		NA	NA		NA	(b)		30 days
Equity funds			39		–		NA		NA	NA		NA	(c)		<30-90 days
Private equity funds			115,568		27,685		100%		13%	36%		51%	NA		NA
Total		$	161,420	$	27,685
Redemption frequency as follows:
(a)	daily (1%), weekly (12%), monthly (55%) and quarterly (32%)
(b)	daily (100%)
(c)	daily (13%), monthly (58%) and quarterly (29%)
		31-Dec-12
							% of		Estimated Liquidation Period of				Investments Redeemable
							Fair Value		Investments Not Redeemable
							Not
		Fair Value		Unfunded			Redeemable		%	%		%	Redemption		Redemption
				Commitments					Next	10-May		Thereafter	Frequency		Notice Period
									5 Years	Years
Alternative investment funds		$	57,890	$	–		NA		NA	NA		NA	(a)		<30-120 days
Debt funds			4		–		NA		NA	NA		NA	(b)		30 days
Equity funds			9,079		–		2%		–%	–%		2%	(c)		30-120 days
Private equity funds			112,444		31,482		100%		13%	39%		48%	NA		NA
Total		$	179,417	$	31,482
Redemption frequency as follows:
(a)	daily (10%), weekly (9%), monthly (38%) and quarterly (43%)
(b)	daily (100%)
(c)	daily (37%) and monthly (61%)
See Note 4 of Notes to Condensed Consolidated Financial Statements for discussion of significant investment strategies for investments valued based on NAV.
Investment Capital Funding Commitments—At September 30, 2013, the Company’s maximum unfunded commitments for capital contributions to investment funds arose from (i) commitments to Corporate Partners II Limited (“CP II”), which amounted to $1,940 for potential “follow-on investments” and/or for fund expenses through the earlier of February 25, 2017 or the liquidation of the fund, (ii) commitments to EGCP III, which amounted to $18,501 through the earlier of October 12, 2016 (i.e., the end of the investment period) for investments and/or expenses (with a portion of the undrawn amount of such commitments as of that date remaining committed until October 12, 2023 in respect of “follow-on investments” and/or fund expenses) or the liquidation of the fund and (iii) commitments to COF2, which amounted to $7,244 through the earlier of November 11, 2016 (i.e., the end of the investment period) for investments and/or fund expenses (with a portion of the undrawn amount of such commitments as of that date remaining committed until November 11, 2019 in respect of “follow-on investments” and/or fund expenses) or the liquidation of the fund.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivatives	6	DERIVATIVES
	The Company enters into forward foreign currency exchange rate contracts, interest rate swaps, interest rate futures, equity and fixed income swaps and other derivative contracts to hedge exposures to fluctuations in currency exchange rates, interest rates and equity and debt prices. The Company reports its derivative instruments separately as assets and liabilities unless a legal right of set-off exists under a master netting agreement enforceable by law. The Company’s derivative instruments are recorded at their fair value, and are included in “other assets” and “other liabilities” on the consolidated statements of financial condition. Gains and losses on the Company’s derivative instruments not designated as hedging instruments are included in “interest income” and “interest expense”, respectively, or “revenue other”, depending on the nature of the underlying item, on the consolidated statements of operations.
	In addition to the derivative instruments described above, the Company records derivative liabilities relating to its obligations pertaining to Lazard Fund Interests awards and other similar deferred compensation arrangements, the fair value of which is based on the value of the underlying investments, adjusted for estimated forfeitures, and is included in “accrued compensation and benefits” in the consolidated statements of financial condition. Changes in the fair value of the derivative liabilities are included in “compensation and benefits” in the consolidated statements of operations, the impact of which equally offsets the changes in the fair value of investments which are currently expected to be delivered upon settlement of Lazard Fund Interests awards and other similar deferred compensation arrangements, which are reported in “revenue-other” in the consolidated statements of operations.
	The tables below present the fair values of the Company’s derivative instruments reported within “other assets” and “other liabilities” and the fair values of the Company’s derivative liabilities relating to its obligations pertaining to Lazard Fund Interests and other similar deferred compensation arrangements (see Note 12 of Notes to Condensed Consolidated Financial Statements) on the accompanying condensed consolidated statements of financial condition as of September 30, 2013 and December 31, 2012:
			September 30,			December 31,
			2013			2012
	Derivative Assets:
	Forward foreign currency exchange rate contracts		$	313		$	893
	Equity and fixed income swaps and other (a)			–			40
			$	313		$	933
	Derivative Liabilities:
	Forward foreign currency exchange rate contracts		$	1,136		$	322
	Interest rate swaps			–			235
	Equity and fixed income swaps (a)			1,825			4,342
	Lazard Fund Interests and other similar deferred compensation arrangements			156,306			97,593
			$	159,267		$	102,492
	(a)	For equity and fixed income swaps, amounts represent the netting of gross derivative assets and liabilities of $480 and $2,305 as of September 30, 2013, respectively, and $0 and $4,342 as of December 31, 2012, respectively, for contracts with the same counterparty under legally enforceable master netting agreements. Such amounts are recorded “net” in “other assets”, with receivables for net cash collateral under such contracts of $14,684 and $15,304 as of September 30, 2013 and December 31, 2012, respectively.
	Net gains (losses) with respect to derivative instruments (predominantly reflected in “revenue-other”) and the Company’s derivative liabilities relating to its obligations pertaining to Lazard Fund Interests and other similar deferred compensation arrangements (included in “compensation and benefits” expense) as reflected on the accompanying condensed consolidated statements of operations for the three month and nine month periods ended September 30, 2013 and 2012, were as follows:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2013			2012			2013			2012
	Forward foreign currency exchange rate contracts		$	(5,310	)	$	(3,377	)	$	(1,705	)	$	(1,248	)
	Lazard Fund Interests and other similar deferred compensation arrangements			(7,519	)		(4,728	)		(7,767	)		(4,639	)
	Equity and fixed income swaps and other			(6,520	)		(7,471	)		(6,872	)		(14,096	)
	Total		$	(19,349	)	$	(15,576	)	$	(16,344	)	$	(19,983	)

Property

Property	9 Months Ended
	Sep. 30, 2013
Property Plant And Equipment [Abstract]
Property	7	PROPERTY
	At September 30, 2013 and December 31, 2012, property consisted of the following:
			Estimated		September 30,		December 31,
			Depreciable		2013		2012
			Life in Years
	Buildings			33		$170,479		$166,560
	Leasehold improvements			20-Mar		173,303		143,408
	Furniture and equipment			10-Mar		146,504		122,125
	Construction in progress					4,128		18,801
	Total					494,414		450,894
	Less - accumulated depreciation and amortization					244,634		225,861
	Property					$249,780		$225,033

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	8	GOODWILL AND OTHER INTANGIBLE ASSETS
	The components of goodwill and other intangible assets at September 30, 2013 and December 31, 2012 are presented below:
			September 30,			December 31,
			2013			2012
	Goodwill		$	350,619		$	364,328
	Other intangible assets (net of accumulated amortization)			25,782			28,494
			$	376,401		$	392,822
	At September 30, 2013 and December 31, 2012, goodwill of $286,078 and $299,787, respectively, was attributable to the Company’s Financial Advisory segment and, at each such respective date, $64,541 of goodwill was attributable to the Company’s Asset Management segment.
	Changes in the carrying amount of goodwill for the nine month periods ended September 30, 2013 and 2012 are as follows:
			Nine Months Ended
			September 30,
			2013			2012
	Balance, January 1		$	364,328		$	356,657
	Business acquisitions			1,601			4,272
	Foreign currency translation adjustments			(15,310	)		3,832
	Balance, September 30		$	350,619		$	364,761
	The gross cost and accumulated amortization of other intangible assets as of September 30, 2013 and December 31, 2012, by major intangible asset category, are as follows:
			September 30, 2013							31-Dec-12
			Gross Cost			Accumulated		Net Carrying		Gross Cost		Accumulated		Net Carrying
						Amortization		Amount				Amortization		Amount
	Success/performance fees		$	30,740		$	10,726	$	20,014	$	30,740	$	10,678	$	20,062
	Management fees, customer relationships and non-compete agreements			33,081			27,313		5,768		33,035		24,603		8,432
			$	63,821		$	38,039	$	25,782	$	63,775	$	35,281	$	28,494
	Amortization expense of intangible assets for the three month and nine month periods ended September 30, 2013 was $877 and $2,758, respectively, and for the three month and nine month periods ended September 30, 2012 was $2,494 and $6,172, respectively. Estimated future amortization expense is as follows:
	Year Ending December 31,		Amortization
			Expense (a)
	2013 (October 1 through December 31)		$	2,589
	2014			11,574
	2015			6,438
	2016			5,181
	Total amortization expense		$	25,782
		(a)	Approximately 45% of intangible asset amortization is attributable to a noncontrolling interest.

Senior_Debt

Senior Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]
Senior Debt	9	SENIOR DEBT
	Senior debt was comprised of the following as of September 30, 2013 and December 31, 2012:
			Initial		Maturity		Annual			Outstanding As Of
			Principal		Date		Interest
			Amount				Rate			September 30,		December 31,
										2013		2012
	Lazard Group 7.125% Senior Notes		$	550,000		5/15/15		7.125	%	$	528,500	$	528,500
	Lazard Group 6.85% Senior Notes			600,000		6/15/17		6.85	%		548,350		548,350
	Lazard Group Credit Facility			150,000		9/25/15		0.76	%		–		–
	Total									$	1,076,850	$	1,076,850
	On September 25, 2012, Lazard Group entered into a $150,000, three-year senior revolving credit facility with a group of lenders (the “Credit Facility”), which expires in September 2015. The Credit Facility replaced a similar revolving credit facility which was terminated as a condition to effectiveness of the Credit Facility. Interest rates under the Credit Facility vary and are based on either a Federal Funds rate or a Eurodollar rate, in each case plus an applicable margin. As of September 30, 2013, the annual interest rate for a loan accruing interest (based on the Federal Funds overnight rate), including the applicable margin, was 0.76%. At September 30, 2013 and December 31, 2012, no amounts were outstanding under the Credit Facility.
	The Credit Facility contains customary terms and conditions, including certain financial covenants. In addition, the Credit Facility, the indenture and the supplemental indentures relating to Lazard Group’s senior notes, contain certain covenants, events of default and other customary provisions, including a customary make-whole provision in the event of early redemption, where applicable. As of September 30, 2013, the Company was in compliance with such provisions. All of the Company’s senior debt obligations are unsecured.
	As of September 30, 2013, the Company had approximately $264,000 in unused lines of credit available to it, including the Credit Facility, and unused lines of credit available to LFB of approximately $54,000 (at September 30, 2013 exchange rates) and Edgewater of $55,000. In addition, LFB has access to the Eurosystem Covered Bond Purchase Program of the Banque de France.
	The Company’s senior debt at September 30, 2013 and December 31, 2012 is carried at historical amounts. At those dates, the fair value of such senior debt outstanding was approximately $1,197,000 and $1,207,000, respectively, and exceeded the aggregate carrying value by approximately $120,000 and $130,000, respectively. The fair value of the Company’s senior debt was based on market quotations. The Company’s senior debt would be categorized within Level 2 of the hierarchy of fair value measurements if carried at fair value.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10	COMMITMENTS AND CONTINGENCIES
	Leases—The Company has various leases and other contractual commitments arising in the ordinary course of business. In the opinion of management, the fulfillment of such commitments, in accordance with their terms, will not have a material adverse effect on the Company’s consolidated financial position or results of operations.
	Guarantees—In the normal course of business, LFB provides indemnifications to third parties to protect them in the event of non-performance by its clients. At September 30, 2013, LFB had $4,337 of such indemnifications and held $3,572 of collateral/counter-guarantees to secure these commitments. The Company believes the likelihood of loss with respect to these indemnities is remote. Accordingly, no liability is recorded in the condensed consolidated statement of financial condition.
	Certain Business Transactions—On July 15, 2009, the Company established a private equity business with Edgewater. Edgewater manages funds primarily focused on buy-out and growth equity investments in middle market companies. The acquisition was structured as a purchase by Lazard Group of interests in a holding company that in turn owns interests in the general partner and management company entities of the current Edgewater private equity funds (the “Edgewater Acquisition”). Following the Edgewater Acquisition, Edgewater’s leadership team retained a substantial economic interest in such entities.
	The aggregate fair value of the consideration recognized by the Company at the acquisition date was $61,624. Such consideration consisted of (i) a one-time cash payment, (ii) 1,142,857 shares of Class A common stock (the “Initial Shares”) and (iii) up to 1,142,857 additional shares of Class A common stock (the “Earnout Shares”) that are subject to earnout criteria and payable over time. The Initial Shares are subject to forfeiture provisions that lapse only upon the achievement of certain performance thresholds and transfer restrictions during the four year period ending December 2014. The Earnout Shares will be issued only if certain performance thresholds are met. As of September 30, 2013 and December 31, 2012, 1,371,992 and 1,209,154 shares, respectively, have been earned because applicable performance thresholds have been satisfied. Such shares are no longer subject to any contingencies. As of December 31, 2012, 686,004 of such shares have been settled, and no additional shares have been settled as of September 30, 2013.
	Consideration Relating To Other Business Acquisitions—For a business acquired in 2013, the Company is obligated to issue a maximum of 107,617 shares of Class A common stock if certain performance thresholds are achieved.
	For a business acquired in 2012, at December 31, 2012, 170,988 shares of Class A common stock (including dividend equivalent shares) were issuable on a non-contingent basis. Such shares were delivered in the first quarter of 2013. The Company is obligated to issue a maximum of 202,650 additional shares of Class A common stock if certain performance thresholds are achieved.
	For a business acquired in 2011, the Company is obligated to pay earnout consideration if certain performance thresholds are achieved. The maximum potential earnout consideration payable by the Company cannot exceed $7,000. Through September 30, 2013, no cash payments relating to the earnout consideration were required.
	Other Commitments—In the normal course of business, LFB enters into commitments to extend credit, predominately at variable interest rates. These commitments have varying expiration dates, are fully collateralized and generally contain requirements for the counterparty to maintain a minimum collateral level. These commitments may not represent future cash requirements as they may expire without being drawn upon. At September 30, 2013, these commitments were not material.
	See Notes 5 and 13 of Notes to Condensed Consolidated Financial Statements for information regarding commitments relating to investment capital funding commitments and obligations to fund our pension plans, respectively.
	The Company has various other contractual commitments arising in the ordinary course of business. In addition, from time to time, LFB enters into underwriting commitments in which it participates as a joint underwriter. The settlement of such transactions are not expected to have a material adverse effect on the Company’s consolidated financial position or results of operations. At September 30, 2013, LFB had no such underwriting commitments.
	In the opinion of management, the fulfillment of the commitments described herein will not have a material adverse effect on the Company’s consolidated financial position or results of operations.
	Legal—The Company is involved from time to time in judicial, regulatory and arbitration proceedings and inquiries concerning matters arising in connection with the conduct of our businesses, including proceedings initiated by former employees alleging wrongful termination. The Company reviews such matters on a case-by-case basis and establishes any required accrual if a loss is probable and the amount of such loss can be reasonably estimated. The Company experiences significant variation in its revenue and earnings on a quarterly basis. Accordingly, the results of any pending matter or matters could be significant when compared to the Company’s earnings in any particular fiscal quarter. The Company believes, however, based on currently available information, that the results of any pending matters, in the aggregate, will not have a material effect on its business or financial condition.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]
Stockholders' Equity	11	STOCKHOLDERS’ EQUITY
	Lazard Group Distributions—As previously described, Lazard Group’s common membership interests are held by subsidiaries of Lazard Ltd and by LAZ-MD Holdings. Pursuant to provisions of the Operating Agreement, Lazard Group distributions in respect of its common membership interests are allocated to the holders of such interests on a pro rata basis. Such distributions represent amounts necessary to fund (i) any dividends Lazard Ltd may declare on its Class A common stock and (ii) tax distributions in respect of income taxes that Lazard Ltd’s subsidiaries and the members of LAZ-MD Holdings incur as a result of holding Lazard Group common membership interests.
	During the nine month periods ended September 30, 2013 and 2012, Lazard Group distributed the following amounts to LAZ-MD Holdings and the subsidiaries of Lazard Ltd (none of which related to tax distributions):
			Nine Months Ended
			September 30,
			2013			2012
	LAZ-MD Holdings		$	565		$	3,729
	Subsidiaries of Lazard Ltd			60,931			66,219
			$	61,496		$	69,948
	Pursuant to Lazard Group’s Operating Agreement, Lazard Group allocates and distributes to its members a substantial portion of its distributable profits in installments, as soon as practicable after the end of each fiscal year. Such installment distributions usually begin in February.
	Exchanges of Lazard Group Common Membership Interests—During the nine month periods ended September 30, 2013 and 2012, Lazard Ltd issued 839,658 and 191,701 shares of Class A common stock, respectively, in connection with the exchanges of a like number of Lazard Group common membership interests (received from members of LAZ-MD Holdings in exchange for a like number of LAZ-MD Holdings exchangeable interests).
	See “Noncontrolling Interests” below for additional information regarding Lazard Ltd’s and LAZ-MD Holdings’ ownership interests in Lazard Group.
	Share Repurchase Program—In February 2011, October 2011, April 2012 and October 2012 the Board of Directors of Lazard Ltd authorized, on a cumulative basis, the repurchase of up to $250,000, $125,000, $125,000 and $200,000, respectively, in aggregate cost of Class A common stock and Lazard Group common membership interests through December 31, 2012, December 31, 2013, December 31, 2013 and December 31, 2014, respectively. The Company’s prior share repurchase authorizations expired on December 31, 2009 and December 31, 2011. The Company expects that the share repurchase program, with respect to the Class A common stock, will continue to be used, among other ways, to offset a portion of the shares that have been or will be issued under the Lazard Ltd 2005 Equity Incentive Plan (the “2005 Plan”) and the Lazard Ltd 2008 Incentive Compensation Plan (the “2008 Plan”). Pursuant to such authorizations, purchases have been made in the open market or through privately negotiated transactions. During the nine month period ended September 30, 2013, the Company made purchases of 2,201,657 Class A common shares, at an aggregate cost of $77,934 (no Lazard Group common membership interests were purchased during such nine month period).
	As of September 30, 2013, $76,132 of the current share repurchase amount authorized as of such date remained available under the share repurchase program, all of which expires December 31, 2014. In addition, under the terms of the 2005 Plan and the 2008 Plan, upon the vesting of restricted stock units (“RSUs”), performance-based restricted stock units (“PRSUs”) and delivery of restricted Class A common stock, shares of Class A common stock may be withheld by the Company to cover its minimum statutory tax withholding requirements (see Note 12 of Notes to Condensed Consolidated Financial Statements).
	In October 2013, the Board of Directors of Lazard Ltd authorized the repurchase of up to an additional $100,000 in aggregate cost of Class A common stock and Lazard Group common membership interests through December 31, 2015.
	Preferred Stock—Lazard Ltd has 15,000,000 authorized shares of preferred stock, par value $0.01 per share, inclusive of its Series A and Series B preferred stock. Series A and Series B preferred shares were issued in connection with certain prior year business acquisitions, are each non-participating securities convertible into Class A common stock and have no voting or dividend rights. As of both September 30, 2013 and December 31, 2012, 7,921 shares of Series A preferred stock were outstanding and no shares of Series B preferred stock were outstanding. At September 30, 2013, no shares of Series A preferred stock were convertible into shares of Class A common stock on a contingent or a non-contingent basis.
	Accumulated Other Comprehensive Income (Loss), Net of Tax (“AOCI”)—The table below reflects the components of AOCI at September 30, 2013 and activity during the nine month period then ended:
			Currency			Interest			Employee			Total				Amount			Total
			Translation			Rate			Benefit			AOCI				Attributable to			Lazard Ltd
			Adjustments			Hedge			Plans							Noncontrolling			AOCI
																Interests
	Balance, January 1, 2013		$	19,405		$	(2,502	)	$	(128,536	)	$	(111,633	)		$	(1,092	)	$	(110,541	)
	Activity January 1 to September 30, 2013:
	Other comprehensive gain (loss) before reclassifications			(18,610	)		–			(2,669	)		(21,279	)			451			(21,730	)
	Adjustments for items reclassified to earnings, net of tax			–			791			3,653			4,444				25			4,419
	Net other comprehensive			(18,610	)		791			984			(16,835	)			476			(17,311	)
	income (loss)
	Balance, September 30, 2013		$	795		$	(1,711	)	$	(127,552	)	$	(128,468	)		$	(616	)	$	(127,852	)
	The table below reflects adjustments for items reclassified out of AOCI, by component, for the three month and nine month periods ended September 30, 2013:
			Three Months Ended			Nine Months Ended
			September 30,			September 30,
			2013			2013
	Amortization of interest rate hedge		$	264	(a)	$	791	(a)
	Amortization relating to employee benefit plans			1,627	(b)		4,859	(b)
	Less - related income taxes			404			1,206
	Net of tax			1,223			3,653
	Total reclassifications, net of tax		$	1,487		$	4,444
	(a)	Included in “interest expense” on the condensed consolidated statements of operations.
	(b)	Included in the computation of net periodic benefit cost (see Note 13 of Notes to Condensed Consolidated Financial Statements). Such amount is included in “compensation and benefits” expense on the condensed consolidated statement of operations.
	Noncontrolling Interests—Noncontrolling interests principally represent interests held in (i) Lazard Group by LAZ-MD Holdings and (ii) Edgewater’s management vehicles that the Company is deemed to control, but does not own.
	The following tables summarize the changes in ownership interests in Lazard Group held by Lazard Ltd and LAZ-MD Holdings during the nine month periods ended September 30, 2013 and 2012:
			Lazard Ltd						LAZ-MD Holdings					Total
														Lazard
														Group
														Common
														Membership
			Common			%			Common			%		Interests
			Membership			Ownership			Membership			Ownership
			Interests						Interests
	Balance, January 1, 2012			123,009,311			94.80%			6,756,779		5.20%			129,766,090
	Activity January 1, 2012 to September 30, 2012:
	Common membership interest activity in connection with:
	Exchanges for Class A common stock			191,701						(191,701	)				–
	Balance, September 30, 2012			123,201,012			94.9	%		6,565,078		5.10%			129,766,090
	Balance, January 1, 2013			128,216,423			98.8	%		1,549,667		1.20%			129,766,090
	Activity January 1, 2013 to September 30, 2013:
	Common membership interest activity in connection with:
	Exchanges for Class A common stock			839,658						(839,658	)				–
	Balance, September 30, 2013			129,056,081			99.5	%		710,009		0.50%			129,766,090
	The change in Lazard Ltd’s ownership in Lazard Group in the nine month periods ended September 30, 2013 and 2012 did not materially impact Lazard Ltd’s stockholders’ equity.
	The tables below summarize net income attributable to noncontrolling interests for the three month and nine month periods ended September 30, 2013 and 2012 and noncontrolling interests as of September 30, 2013 and December 31, 2012 in the Company’s condensed consolidated financial statements:
			Net Income (Loss) Attributable To
			Noncontrolling Interests
			Three Months Ended						Nine Months Ended
September 30,					September 30,
		2013			2012			2013			2012
Edgewater		$	2,018		$	(1,704	)	$	4,671		$	2,168
LAZ-MD Holdings			365			1,937			862			4,956
Other			83			139			(210	)		93
Total		$	2,466		$	372		$	5,323		$	7,217
		Noncontrolling Interests As Of
		September 30,			December 31,
		2013			2012
Edgewater		$	71,075		$	75,262
LAZ-MD Holdings			2,629			5,405
Other			583			1,217
Total		$	74,287		$	81,884
Dividend Declared, October 2013—On October 23, 2013, the Board of Directors of Lazard Ltd declared a quarterly dividend of $0.25 per share on its Class A common stock, payable on November 22, 2013, to stockholders of record on November 4, 2013.

Incentive_Plans

Incentive Plans	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Incentive Plans	12	INCENTIVE PLANS
	Share-Based Incentive Plan Awards
	A description of Lazard Ltd’s 2005 Plan and 2008 Plan and activity with respect thereto during the nine month periods ended September 30, 2013 and 2012, is presented below.
	Shares Available Under the 2005 Plan and 2008 Plan
	The 2005 Plan authorizes the issuance of up to 25,000,000 shares of Class A common stock pursuant to the grant or exercise of stock options, stock appreciation rights, RSUs and other equity-based awards. Each stock unit or similar award granted under the 2005 Plan represents a contingent right to receive one share of Class A common stock, at no cost to the recipient. The fair value of such awards is generally determined based on the closing market price of Class A common stock at the date of grant.
	In addition to the shares available under the 2005 Plan, additional shares of Class A common stock are available under the 2008 Plan. The maximum number of shares available under the 2008 Plan is based on a formula that limits the aggregate number of shares that may, at any time, be subject to awards that are considered “outstanding” under the 2008 Plan to 30% of the then-outstanding shares of Class A common stock (treating, for this purpose, the then-outstanding exchangeable interests of LAZ-MD Holdings on a “fully-exchanged” basis as described in the 2008 Plan).
	The following reflects the amortization expense recorded with respect to share-based incentive plans within “compensation and benefits” expense (with respect to RSUs, PRSUs and restricted stock awards) and “professional services” expense (with respect to deferred stock units (“DSUs”)) within the Company’s accompanying condensed consolidated statements of operations:
			Three Months  Ended							Nine Months Ended
			September 30,							September 30,
			2013			2012				2013		2012
	Share-based incentive awards:
	RSUs (a)		$	46,095		$	65,952			$	163,184	$	211,271
	PRSUs			6,467			–				8,900		–
	Restricted stock (b)			2,627			1,659				9,712		7,538
	DSUs			71			78				1,545		1,366
	Total		$	55,260		$	67,689			$	183,341	$	220,175
	(a)	Includes $0 and $9,099 during the three month and nine month periods ended September 30, 2013 relating to the Cost Saving Initiatives (see Note 14 of Notes to Condensed Consolidated Financial Statements).
	(b)	Includes $0 and $247 during the three month and nine month periods ended September 30, 2013 relating to the Cost Saving Initiatives.
	The ultimate amount of compensation and benefits expense relating to share-based awards is dependent upon the actual number of shares of Class A common stock that vest. The Company periodically assesses the forfeiture rates used for such estimates. A change in estimated forfeiture rates results in a cumulative adjustment to previously recorded compensation and benefits expense and also would cause the aggregate amount of compensation expense recognized in future periods to differ from the estimated unrecognized compensation expense described below.
	For purposes of calculating diluted net income per share, RSU and restricted stock awards are included in the diluted weighted average shares of Class A common stock outstanding using the “treasury stock” method. PRSUs are included in the diluted weighted average shares of Class A common stock outstanding to the extent the performance conditions are met at the end of the reporting period, also using the “treasury stock” method.
	The Company’s incentive plans are described below.
	RSUs and DSUs
	RSUs generally require future service as a condition for the delivery of the underlying shares of Class A common stock (unless the recipient is then eligible for retirement under the Company’s retirement policy) and convert into Class A common stock on a one-for-one basis after the stipulated vesting periods. PRSUs, which are a form of RSUs that are also subject to service-based vesting conditions, have additional conditions and are described below. The grant date fair value of the RSUs, net of an estimated forfeiture rate, is amortized over the vesting periods or requisite service periods (generally one-third after two years, and the remaining two-thirds after the third year), and is adjusted for actual forfeitures over such periods.
	RSUs generally include a dividend participation right that provides that during vesting periods each RSU is attributed additional RSUs (or fractions thereof) equivalent to any ordinary quarterly dividends paid on Class A common stock during such period. During the nine month periods ended September 30, 2013 and 2012, issuances of RSUs pertaining to such dividend participation rights and respective charges to “retained earnings”, net of estimated forfeitures (with corresponding credits to “additional paid-in-capital”), consisted of the following:
			Nine Months  Ended
			September 30,
			2013				2012
	Number of RSUs issued				250,834				479,958
	Charges to retained earnings, net of estimated forfeitures			$	8,216			$	11,770
	Non-executive members of the Board of Directors receive approximately 55% of their annual compensation for service on the Board of Directors and its committees in the form of DSUs, which resulted in 39,315 and 49,982 DSUs granted during the nine month periods ended September 30, 2013 and 2012, respectively. Their remaining compensation is payable in cash, which they may elect to receive in the form of additional DSUs under the Directors’ Fee Deferral Unit Plan described below. DSUs are convertible into Class A common stock at the time of cessation of service to the Board and, for purposes of calculating diluted net income per share, are included in the diluted weighted average shares of Class A common stock outstanding using the “treasury stock” method. DSUs include a cash dividend participation right equivalent to any ordinary quarterly dividends paid on Class A common stock, and resulted in nominal cash payments for the nine month periods ended September 30, 2013 and 2012.
	The Company’s Directors’ Fee Deferral Unit Plan permits its Non-Executive Directors to elect to receive additional DSUs in lieu of some or all of their cash fees. The number of DSUs that shall be granted to a Non-Executive Director pursuant to this election will equal the value of cash fees that the applicable Non-Executive Director has elected to forego pursuant to such election, divided by the market value of a share of Class A common stock on the date on which the foregone cash fees would otherwise have been paid. During the nine month periods ended September 30, 2013 and 2012, 5,880 and 7,988 DSUs, respectively, had been granted pursuant to such Plan.
	DSU awards are expensed at their fair value on their date of grant, inclusive of amounts related to the Directors’ Fee Deferral Unit Plan.
	The following is a summary of activity relating to RSUs and DSUs during the nine month periods ended September 30, 2013 and 2012:
			RSUs							DSUs
			Units			Weighted				Units		Weighted
						Average						Average
						Grant Date						Grant Date
						Fair Value						Fair Value
	Balance, January 1, 2013			21,481,131		$	33.92				204,496	$	31.47
	Granted (including 250,834 RSUs relating to dividend participation)			4,862,379		$	36.92				45,195	$	34.18
	Forfeited			(239,117	)	$	34.63				–		–
	Vested			(9,363,792	)	$	34.78				–		–
	Balance, September 30, 2013			16,740,601		$	34.3				249,691	$	31.96
	Balance, January 1, 2012			20,751,829		$	36.84				140,660	$	34.83
	Granted (including 479,958 RSUs relating to dividend participation)			8,121,632		$	27.56				57,970	$	23.57
	Forfeited			(401,065	)	$	35.49				–		–
	Vested			(4,425,534	)	$	34.43				–		–
	Balance, September 30, 2012			24,046,862		$	34.16				198,630	$	31.54
	In connection with RSUs which vested during the nine month periods ended September 30, 2013 and 2012, the Company satisfied its minimum statutory tax withholding requirements in lieu of issuing 3,471,813 and 1,331,812 shares of Class A common stock in the respective nine month periods. Accordingly, 5,891,979 and 3,093,722 shares of Class A common stock held by the Company were delivered during the nine month periods ended September 30, 2013 and 2012, respectively. In addition, during the nine month period ended September 30, 2012, 42,432 shares of previously delivered Class A common stock were forfeited by certain former employees and returned to the Company.
	During the fourth quarter of 2012, 958,213 RSUs were modified through forward purchase agreements into liability awards. Such liability awards were settled on March 1, 2013 for $28,612. During the nine month period ended September 30, 2013, compensation expense of $1,690 was recorded for such liability awards.
	As of September 30, 2013, unrecognized RSU compensation expense, adjusted for estimated forfeitures, was approximately $196,000, with such unrecognized compensation expense expected to be recognized over a weighted average period of approximately 1.2 years subsequent to September 30, 2013.
	Restricted Stock
	The following is a summary of activity related to shares of restricted Class A common stock associated with compensation arrangements during the nine month periods ended September 30, 2013 and 2012:
			Restricted			Weighted
			Shares			Average
						Grant Date
						Fair Value
	Balance, January 1, 2013			1,972,609		$	34.85
	Granted			368,736		$	36.74
	Forfeited			(35,794	)	$	33.35
	Vested			(1,728,509	)	$	36
	Balance, September 30, 2013			577,042		$	32.72
	Balance, January 1, 2012			95,332		$	37.63
	Granted/Exchanged			577,323		$	29.25
Forfeited			(21,178	)	$	29.51
Vested			(186,180	)	$	31.6
Balance, September 30, 2012			465,297		$	30.02
In connection with shares of restricted Class A common stock that vested during the nine month periods ended September 30, 2013 and 2012, the Company satisfied its minimum statutory tax withholding requirements in lieu of delivering 18,631 and 28,129 shares of Class A common stock during the respective periods. Accordingly, 1,709,878 and 158,051 shares of Class A common stock held by the Company were delivered during the nine month periods ended September 30, 2013 and 2012, respectively.
The awards include a cash dividend participation right equivalent to any ordinary quarterly dividends paid on Class A common stock during the period, which will vest concurrently with the underlying restricted stock award. At September 30, 2013, unrecognized restricted stock expense was approximately $9,000, with such expense to be recognized over a weighted average period of approximately 1.5 years subsequent to September 30, 2013.
PRSUs
During the nine month period ended September 30, 2013, the Company granted 448,128 PRSUs. The PRSUs are subject to both performance-based and service-based vesting conditions. The number of shares of Class A common stock that a recipient will receive upon vesting of a PRSU will be calculated by reference to certain performance metrics that relate to the Company’s performance over the three-year period beginning on January 1, 2012 and ending on December 31, 2014. The target number of shares of Class A common stock subject to each PRSU is one; however, based on the achievement of the performance criteria, the number of shares of Class A common stock that may be received in connection with each PRSU can range from zero to three times the target number. The PRSUs granted in 2013 will vest 33% in March 2015 and 67% in March 2016, provided the applicable service and performance conditions are satisfied. In addition, the performance metrics applicable to each PRSU will be evaluated on an annual basis at the end of each fiscal year during the performance period and, if the Company has achieved a threshold level of performance with respect to the fiscal year, 25% of the target number of shares of Class A common stock subject to each PRSU will no longer be at risk of forfeiture based on the achievement of performance criteria. PRSUs generally include dividend participation rights.
Compensation expense recognized for PRSU awards is determined by multiplying the number of shares of Class A common stock underlying such awards that, based on the Company’s estimate, are considered probable of vesting, by the grant date fair value of $36.11 per share. As of September 30, 2013, the total estimated unrecognized compensation expense for PRSUs granted in 2013 was approximately $23,000, and the Company expects to amortize such expense over a weighted-average period of approximately 1.7 years.
Lazard Fund Interests and Other Similar Deferred Compensation Arrangements
Commencing in February 2011, the Company granted Lazard Fund Interests to eligible employees. In connection with the Lazard Fund Interests and other similar deferred compensation arrangements, which generally require future service as a condition for vesting, the Company recorded a prepaid compensation asset and a corresponding compensation liability on the grant date based upon the fair value of the award. The prepaid asset is amortized on a straight-line basis over the applicable vesting periods or requisite service periods (which are generally similar to the comparable periods for RSUs), and is charged to “compensation and benefits” expense within the Company’s consolidated statement of operations. Lazard Fund Interests and similar deferred compensation arrangements that do not require future service are expensed immediately. The related compensation liability is accounted for at fair value as a derivative liability, which contemplates the impact of estimated forfeitures, and is adjusted for changes in fair value primarily related to changes in value of the underlying investments.
The following is a summary of activity relating to Lazard Fund Interests and other similar deferred compensation arrangements during the nine month periods ended September 30, 2013 and 2012:
		Prepaid			Compensation
		Compensation			Liability
		Asset
Balance, January 1, 2013		$	47,445		$	97,593
Granted			72,217			72,217
Settled			–			(22,903	)
Forfeited			(765	)		(985	)
Amortization			(44,195	)		–
Change in fair value related to:
Increase in fair value of underlying investments			–			7,767
Adjustment for estimated forfeitures			–			3,175
Other			(217	)		(558	)
Balance, September 30, 2013		$	74,485		$	156,306
		Prepaid			Compensation
		Compensation			Liability
		Asset
Balance, January 1, 2012		$	17,782		$	29,900
Granted			64,658			64,658
Settled			–			(8,640	)
Forfeited			(1,607	)		(1,706	)
Amortization			(24,508	)		–
Change in fair value related to:
Increase in fair value of underlying investments			–			4,639
Adjustment for estimated forfeitures			–			2,202
Other			101			–
Balance, September 30, 2012		$	56,426		$	91,053
The amortization of the prepaid compensation asset will generally be recognized over a weighted average period of approximately 1.7 years subsequent to September 30, 2013.
The following is a summary of the impact of Lazard Fund Interests and other similar deferred compensation arrangements on “compensation and benefits” expense within the accompanying condensed consolidated statements of operations for the three month and nine month periods ended September 30, 2013 and 2012:
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2013			2012				2013		2012
Compensation expense:
Amortization, net of forfeitures (a)		$	15,049		$	9,626			$	47,150	$	26,611
Change in fair value of underlying investments			7,519			4,728				7,767		4,639
Total		$	22,568		$	14,354			$	54,917	$	31,250
(a)	Includes $0 and $2,665 during the three month and nine month periods ended September 30, 2013 relating to the Cost Saving Initiatives.

Employee_Benefit_Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2013
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	13	EMPLOYEE BENEFIT PLANS
	The Company provides retirement and other post-retirement benefits to certain of its employees through defined benefit pension plans (the “pension plans”) and, in the U.S., a partially funded contributory post-retirement plan covering qualifying U.S. employees (the “medical plan” and together with the pension plans, the “post-retirement plans”). The Company also offers defined contribution plans. The post-retirement plans generally provide benefits to participants based on average levels of compensation. Expenses related to the Company’s employee benefit plans are included in “compensation and benefits” expense on the consolidated statements of operations.
	Employer Contributions to Pension Plans—The Company’s funding policy for its U.S. and non-U.S. pension plans is to fund when required or when applicable upon an agreement with the plans’ Trustees. Management also evaluates from time to time whether to make voluntary contributions to the plans. The Company did not make a contribution to the U.S. pension plans during the nine month period ended September 30, 2013.
	On April 30, 2012, the Company and the Trustees of the U.K. pension plans concluded the December 31, 2010 triennial valuations of the plans. In connection with such valuations and a previously negotiated agreement with the Trustees, the Company and the Trustees agreed upon pension funding terms (the “agreement”) (which superseded the terms of an agreement reached in June 2009 with respect to the previous triennial valuation as of December 31, 2007) whereby the Company: (i) made a contribution in December 2011 to the plans of 2.3 million British pounds ($3,687 at December 31, 2011 exchange rates) from a previously established escrow account, (ii) agreed to make contributions of 1 million British pounds during each year from 2012 through 2020 inclusive, and (iii) amended the previous escrow arrangement into an account security arrangement covering 10.2 million British pounds, committing to make annual contributions of 1 million British pounds into such account security arrangement during each year from 2014 through 2020, inclusive. It was further agreed that, to the extent that the value of the plans’ assets falls short of the funding target for June 1, 2020 that has been agreed upon with the Trustees, the assets from the account security arrangement would be released into the plans at that date. Additionally, the Company agreed to fund the expenses of administering the plans, including certain regulator levies and the cost of other professional advisors to the plans. The terms of the agreement are subject to adjustment based on the results of subsequent triennial valuations. The aggregate amount in the account security arrangement was approximately $16,500 at both September 30, 2013 and December 31, 2012 and has been recorded in “cash deposited with clearing organizations and other segregated cash” on the accompanying condensed consolidated statements of financial condition. Income on the account security arrangement accretes to the Company and is recorded in interest income.
	During the nine month period ended September 30, 2013, the Company contributed 1 million British pounds ($1,545 at September 30, 2013 exchange rates) to these U.K. pension plans, and no contributions were required to be made to other non-U.S. pension plans.
	The following table summarizes the components of net periodic benefit cost related to the Company’s post-retirement plans for the three month and nine month periods ended September 30, 2013 and 2012:
			Pension Plans						Medical Plan
			Three Months Ended September 30,
			2013			2012			2013		2012
	Components of Net Benefit Cost (Credit):
	Service cost		$	315		$	166		$	12	$	15
	Interest cost			6,744			6,862			46		53
	Expected return on plan assets			(6,701	)		(6,637	)		–		–
	Amortization of:
	Prior service cost			708			668			–		–
	Net actuarial loss			919			412			–		–
	Net benefit cost		$	1,985		$	1,471		$	58	$	68
			Pension Plans						Medical Plan
			Nine Months Ended September 30,
			2013			2012			2013		2012
	Components of Net Benefit Cost (Credit):
	Service cost		$	938		$	504		$	39	$	45
	Interest cost			20,193			20,649			137		158
	Expected return on plan assets			(20,090	)		(19,931	)		–		–
	Amortization of:
	Prior service cost			2,114			2,056			–		–
	Net actuarial loss			2,745			1,243			–		–
	Settlement loss (a)			–			886			–		–
	Net benefit cost		$	5,900		$	5,407		$	176	$	203
	(a)	During the nine month period ended September 30, 2012, the Company’s pension plans in the U.S. made lump sum benefit payments in excess of the plans’ annual service and interest costs, which, under U.S. GAAP, requires that the plans’ obligations and assets be remeasured. The remeasurement of the plans resulted in the recognition of actuarial losses totaling $1,935 recorded in “other comprehensive income (loss), net of tax” (“OCI”), which, combined with a settlement loss of $886 recognized in “compensation and benefits” expense, resulted in a net charge to OCI of $1,049.

Cost_Saving_Initiatives

Cost Saving Initiatives	9 Months Ended
	Sep. 30, 2013
Restructuring And Related Activities [Abstract]
Cost Saving Initiatives	14	COST SAVING INITIATIVES
	In October 2012, the Company announced cost saving initiatives (the “Cost Saving Initiatives”) relating to the Company’s operations. These initiatives include streamlining our corporate structure and consolidating support functions; realigning our investments into areas with potential for the greatest long-term return; the settlement of certain contractual obligations; occupancy cost reduction; and creating greater flexibility to retain and attract the best people and invest in new growth areas.
	Expenses associated with the implementation of the Cost Saving Initiatives were completed during the second quarter of 2013. The Company incurred these expenses, by segment, as reflected in the tables below:
			Financial			Asset			Corporate			Total
			Advisory			Management
	Nine Month Period Ended September 30, 2013:
	Compensation and benefits		$	45,746		$	236		$	5,417		$	51,399
	Other			2,033			(1	)		11,272			13,304
	Total		$	47,779		$	235		$	16,689		$	64,703
			Financial			Asset			Corporate			Total
			Advisory			Management
	Cumulative October 2012 Through September 30, 2013:
	Compensation and benefits		$	121,879		$	12,292		$	17,215		$	151,386
	Other			3,432			732			11,729			15,893
	Total		$	125,311		$	13,024		$	28,944		$	167,279
	Activity related to the obligations pursuant to the Cost Saving Initiatives during the nine month period ended September 30, 2013 was as follows:
			Accrued			Other			Total
			Compensation			Liabilities
			and Benefits
	Balance, January 1, 2013		$	46,128		$	1,714		$	47,842
	New charges			51,399			13,304			64,703
	Less:
	Non-cash charges			(12,007	)		(3,387	)		(15,394	)
	Settlements			(68,813	)		(2,299	)		(71,112	)
	Balance, September 30, 2013		$	16,707		$	9,332		$	26,039

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income Taxes	15	INCOME TAXES
	As a result of its indirect investment in Lazard Group, Lazard Ltd, through certain of its subsidiaries, is subject to U.S. federal income taxes on its portion of Lazard Group’s operating income. Although a portion of Lazard Group’s income is subject to U.S. federal income taxes, Lazard Group primarily operates in the U.S. as a limited liability company that is treated as a partnership for U.S. federal income tax purposes. As a result, Lazard Group’s income from its U.S. operations is generally not subject to U.S. federal income taxes because such income is attributable to its partners. In addition, Lazard Group is subject to New York City Unincorporated Business Tax (“UBT”) which is attributable to Lazard Group’s operations apportioned to New York City. UBT is incremental to the U.S. federal statutory tax rate. Outside the U.S., Lazard Group operates principally through subsidiary corporations that are subject to local income taxes.
	The Company recorded income tax provisions of $18,370 and $31,335 for the three month and nine month periods ended September 30, 2013, respectively, and $13,053 and $32,191 for the three month and nine month periods ended September 30, 2012, respectively, representing effective tax rates of 22.6%, 21.8%, 27.9% and 24.9%, respectively. The difference between the U.S. federal statutory rate of 35.0% and the effective tax rates reflected above principally relates to (i) Lazard Group primarily operating as a limited liability company in the U.S., (ii) taxes payable to foreign jurisdictions that are not offset against U.S. income taxes, (iii) foreign source income (loss) not subject to U.S. income taxes (including interest on intercompany financings), (iv) Lazard Group’s income from U.S. operations attributable to noncontrolling interests, and (v) U.S. state and local taxes (primarily UBT), which are incremental to the U.S. federal statutory tax rate.
	Substantially all of Lazard’s foreign operations are conducted in “pass-through” entities for U.S. income tax purposes and the Company provides for U.S. income taxes on a current basis for substantially all of those earnings. The repatriation of prior earnings attributable to “non-pass-through” entities would not result in the recognition of a material amount of additional U.S. income taxes.
	Tax Receivable Agreement
	The redemption of historical partner interests in connection with the Company’s separation and recapitalization that occurred in May 2005 and subsequent exchanges of LAZ-MD Holdings exchangeable interests for shares of Class A common stock have resulted, and future exchanges of LAZ-MD Holdings exchangeable interests for shares of Class A common stock may result, in increases in the tax basis of the tangible and intangible assets of Lazard Group. The tax receivable agreement dated as of May 10, 2005 with LFCM Holdings LLC (“LFCM Holdings”, see Note 17 below) requires the Company to pay LFCM Holdings 85% of the cash savings, if any, in U.S. federal, state and local income tax or franchise tax that the Company actually realizes as a result of the above-mentioned increases in tax basis. The Company calculates this provision annually and includes such amounts in operating expenses on its consolidated statements of operations once the results of operations for the full year are known. Based on the financial results for the applicable annual periods, there is no provision for such payments in the nine month periods ended September 30, 2013 and 2012. If any provision is required pursuant to the tax receivable agreement, such amount would be fully offset by a reduction in the Company’s income tax expense.

Net_Income_Per_Share_of_Class_

Net Income Per Share of Class A Common Stock	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]
Net Income Per Share of Class A Common Stock	16	NET INCOME PER SHARE OF CLASS A COMMON STOCK
	The Company’s basic and diluted net income per share calculations for the three month and nine month periods ended September 30, 2013 and 2012 are computed as described below.
	Basic Net Income Per Share
	Numerator—utilizes net income attributable to Lazard Ltd for the respective periods, plus applicable adjustments to such net income associated with the inclusion of shares of Class A common stock issuable on a non-contingent basis.
	Denominator—utilizes the weighted average number of shares of Class A common stock outstanding for the respective periods, plus applicable adjustments to such shares associated with shares of Class A common stock issuable on a non-contingent basis.
	Diluted Net Income Per Share
	Numerator—utilizes net income attributable to Lazard Ltd for the respective periods, as in the basic net income per share calculation described above, plus, to the extent applicable and dilutive, (i) changes in net income attributable to noncontrolling interests resulting from assumed Class A common stock issuances in connection with share-based incentive compensation and, on an “as-if-exchanged” basis, amounts applicable to LAZ-MD Holdings exchangeable interests and (ii) income tax related to (i) above.
	Denominator—utilizes the weighted average number of shares of Class A common stock outstanding for the respective periods, as in the basic net income per share calculation described above, plus, to the extent dilutive, the incremental number of shares of Class A common stock to settle share-based incentive compensation and LAZ-MD Holdings exchangeable interests, using the “treasury stock” method or the “as-if-exchanged” basis, as applicable.
	The calculations of the Company’s basic and diluted net income per share and weighted average shares outstanding for the three month and nine month periods ended September 30, 2013 and 2012 are presented below:
			Three Months Ended				Nine Months Ended
			September 30,				September 30,
			2013		2012		2013		2012
	Net income attributable to Lazard Ltd		$	60,282		$33,301		$106,995		$89,674
	Add - adjustment associated with Class A common stock issuable on a non-contingent basis			–		3		–		6
	Net income attributable to Lazard Ltd - basic			60,282		33,304		106,995		89,680
	Add - dilutive effect, as applicable, of:
	Adjustments to income relating to interest expense and changes in net income attributable to noncontrolling interests resulting from assumed Class A common stock issuances in connection with share-based incentive compensation and exchangeable interests, net of tax			316		1,804		787		4,680
	Net income attributable to Lazard Ltd - diluted			$60,598		$35,108		$107,782		$94,360
	Weighted average number of shares of Class A common stock outstanding			121,441,956		114,689,712		119,797,545		116,949,317
	Add - adjustment for shares of Class A common stock issuable on a non-contingent basis			757,998		913,639		758,502		740,087
	Weighted average number of shares of Class A common stock outstanding - basic			122,199,954		115,603,351		120,556,047		117,689,404
	Add - dilutive effect, as applicable, of:
	Weighted average number of incremental shares of Class A common stock issuable from share-based incentive compensation and exchangeable interests			12,042,190		19,776,685		12,617,953		17,847,646
	Weighted average number of shares of Class A common stock outstanding - diluted			134,242,144		135,380,036		133,174,000		135,537,050
	Net income attributable to Lazard Ltd per share of Class A common stock:
	Basic			$0.49		$0.29		$0.89		$0.76
	Diluted			$0.45		$0.26		$0.81		$0.70

Related_Parties

Related Parties	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]
Related Parties	17	RELATED PARTIES
	Amounts receivable from, and payable to, related parties are set forth below:
			September  30,		December 31,
			2013		2012
	Receivables
	LFCM Holdings		$	13,015	$	20,529
	Other			1,261		3,272
	Total		$	14,276	$	23,801
	Payables
	LFCM Holdings		$	4,335	$	2,943
	Other			360		705
	Total		$	4,695	$	3,648
	LFCM Holdings
	LFCM Holdings owns and operates the capital markets business and fund management activities, as well as other specified non-operating assets and liabilities, that were transferred to it by Lazard Group (referred to as the “separated businesses”) in May 2005 and is owned by various former and current working members, including certain of Lazard’s former and current managing directors (which also include the Company’s executive officers) who were or are also members of LAZ-MD Holdings. In addition to the master separation agreement, dated as of May 10, 2005, by and among Lazard Ltd, Lazard Group, LAZ-MD Holdings and LFCM Holdings (the “master separation agreement”), which effected the separation and recapitalization that occurred in May 2005, LFCM Holdings entered into certain agreements that addressed various business matters associated with the separation, including agreements related to administrative and support services (the “administrative services agreement”), employee benefits, insurance matters and licensing. In addition, LFCM Holdings and Lazard Group entered into a business alliance agreement (the “business alliance agreement”). Certain of these agreements are described in more detail in the Company’s Form 10-K.
	For the three month and nine month periods ended September 30, 2013, amounts recorded by Lazard Group relating to the administrative services agreement amounted to $534 and $1,466, respectively, and net referral fees for underwriting, private placement, M&A and restructuring transactions under the business alliance agreement amounted to $1,633 and $1,163, respectively. For the three month and nine month periods ended September 30, 2012, amounts recorded by Lazard Group relating to the administrative services agreement amounted to $666 and $2,181, respectively, and net referral fees for underwriting, private placement, M&A and restructuring transactions under the business alliance agreement amounted to $182 and $4,548, respectively. Amounts relating to the administrative services agreement are reported as reductions to operating expenses. Net referral fees for underwriting transactions under the business alliance agreement are reported in “revenue-other”. Net referral fees for private placement, M&A and restructuring transactions under the business alliance agreement are reported in advisory fee revenue.
	Receivables from LFCM Holdings and its subsidiaries as of September 30, 2013 and December 31, 2012 include $5,038 and $14,299, respectively, related to administrative and support services and other receivables, which include sublease income and reimbursement of expenses incurred on behalf of LFCM Holdings, and $7,977 and $6,230, respectively, related to referral fees for underwriting and private placement transactions. Payables to LFCM Holdings and its subsidiaries at September 30, 2013 and December 31, 2012 include $4,335 and $2,943, respectively, primarily relating to referral fees for Financial Advisory transactions.
	Other
	Other receivables and payables at September 30, 2013 and December 31, 2012 primarily relate to referral fees for M&A transactions with MBA Lazard Holdings S.A. and its affiliates, an Argentina-based group in which the Company has a 50% ownership interest, and, at December 31, 2012, a related party loan.
	LAZ-MD Holdings
	Lazard Group provides certain administrative and support services to LAZ-MD Holdings through an administrative services agreement, with such services generally to be provided until December 31, 2014 unless terminated earlier because of a change in control of either party. Lazard Group charges LAZ-MD Holdings for these services based on Lazard Group’s cost allocation methodology and, for the three month and nine month periods ended September 30, 2013, such charges amounted to $250 and $750, respectively. For the three month and nine month periods ended September 30, 2012, such charges amounted to $188 and $563, respectively.

Regulatory_Authorities

Regulatory Authorities	9 Months Ended
	Sep. 30, 2013
Banking And Thrift [Abstract]
Regulatory Authorities	18	REGULATORY AUTHORITIES
	LFNY is a U.S. registered broker-dealer and is subject to the net capital requirements of Rule 15c3-1 under the Exchange Act. Under the basic method permitted by this rule, the minimum required net capital, as defined, is a specified fixed percentage (6  2/3%) of total aggregate indebtedness recorded in LFNY’s Financial and Operational Combined Uniform Single (“FOCUS”) report filed with the Financial Industry Regulatory Authority (“FINRA”), or $100, whichever is greater. At September 30, 2013, LFNY’s regulatory net capital was $84,678, which exceeded the minimum requirement by $81,181.
	Certain U.K. subsidiaries of the Company, including LCL, Lazard Fund Managers Limited and Lazard Asset Management Limited (the “U.K. Subsidiaries”) are regulated by the Financial Conduct Authority. At September 30, 2013, the aggregate regulatory net capital of the U.K. Subsidiaries was $66,007, which exceeded the minimum requirement by $51,404.
	CFLF, under which asset management and commercial banking activities are carried out in France, is subject to regulation by the ACPR for its banking activities conducted through its subsidiary, LFB. In addition, the investment services activities of the Paris group, exercised through LFB and other subsidiaries of CFLF, primarily LFG (asset management), are subject to regulation and supervision by the Autorité des Marchés Financiers. At September 30, 2013, the consolidated regulatory net capital of CFLF was $192,042, which exceeded the minimum requirement set for regulatory capital levels by $158,224.
	Certain other U.S. and non-U.S. subsidiaries are subject to various capital adequacy requirements promulgated by various regulatory and exchange authorities in the countries in which they operate. At September 30, 2013, for those subsidiaries with regulatory capital requirements, their aggregate net capital was $113,317, which exceeded the minimum required capital by $75,584.
	At September 30, 2013, each of these subsidiaries individually was in compliance with its regulatory capital requirements.
	Lazard Ltd had been subject to supervision by the SEC as a Supervised Investment Bank Holding Company (“SIBHC”). As a SIBHC, Lazard Ltd was subject to group-wide supervision, which required it to compute allowable capital and risk allowances on a consolidated basis. However, pursuant to Section 617 of the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”), the SEC’s SIBHC program was eliminated on July 21, 2011.
	Pursuant to the consolidated supervision rules in the European Union, LFB, in particular, as a French credit institution, is required to be supervised by a regulatory body, either in the U.S. or in the European Union. During the third quarter of 2013, the Company and the ACPR agreed on terms for the consolidated supervision of LFB and certain other non-financial advisory European subsidiaries of the Company (referred to herein, on a combined basis, as the “combined European regulated group”) under such rules. Under this new supervision, the combined European regulated group will be required to comply with periodic financial, regulatory net capital and other reporting obligations. Additionally, the combined European regulated group, together with our European financial advisory entities, will be required to perform an annual risk assessment and provide certain other information on a periodic basis, including financial reports and information relating to financial performance, balance sheet data and capital structure (which is similar to the information that we have already been providing informally). This new supervision under, and provision of information to, the ACPR is expected to become effective on December 31, 2013.
	The Dodd-Frank Act and rules and regulations that may be adopted in countries in which we operate (including regulations that have not yet been proposed) could affect us in other ways.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]
Segment Information	19	SEGMENT INFORMATION
	The Company’s reportable segments offer different products and services and are managed separately, as different levels and types of expertise are required to effectively manage the segments’ transactions. Each segment is reviewed to determine the allocation of resources and to assess its performance. The Company’s principal operating activities are included in two business segments as described in Note 1 above - Financial Advisory and Asset Management. In addition, as described in Note 1 above, the Company records selected other activities in its Corporate segment.
	The Company’s segment information for the three month and nine month periods ended September 30, 2013 and 2012 was prepared using the following methodology:
		•		Revenue and expenses directly associated with each segment are included in determining operating income.
		•		Expenses not directly associated with specific segments are allocated based on the most relevant measures applicable, including headcount, square footage and other factors.
		•		Segment assets are based on those directly associated with each segment, and include an allocation of certain assets relating to various segments, based on the most relevant measures applicable, including headcount, square footage and other factors.
	The Company allocates investment gains and losses, interest income and interest expense among the various segments based on the segment in which the underlying asset or liability is reported.
	Each segment’s operating expenses include (i) compensation and benefits expenses incurred directly in support of the businesses and (ii) other operating expenses, which include directly incurred expenses for occupancy and equipment, marketing and business development, technology and information services, professional services, fund administration and outsourced services and indirect support costs (including compensation and other operating expenses related thereto) for administrative services. Such administrative services include, but are not limited to, accounting, tax, legal, facilities management and senior management activities.
	Management evaluates segment results based on net revenue and operating income (loss) and believes that the following information provides a reasonable representation of each segment’s contribution with respect to net revenue, operating income (loss) and total assets:
					Three Months Ended							Nine Months Ended
					September 30,							September 30,
					2013				2012			2013(a)			2012
	Financial Advisory		Net Revenue		$	233,842			$	219,973		$	665,611		$	739,793
			Operating Expenses			218,015				212,449			674,689			693,546
			Operating Income (Loss)		$	15,827			$	7,524		$	(9,078	)	$	46,247
	Asset Management		Net Revenue		$	252,094			$	221,516		$	741,618		$	647,096
			Operating Expenses			168,895				160,869			511,526			477,989
			Operating Income		$	83,199			$	60,647		$	230,092		$	169,107
	Corporate		Net Revenue (Expense)		$	(5,582	)		$	(12,683	)	$	(34,567	)	$	(35,134	)
			Operating Expenses			12,326				8,762			42,794			51,138
			Operating Income (Loss)		$	(17,908	)		$	(21,445	)	$	(77,361	)	$	(86,272	)
	Total		Net Revenue		$	480,354			$	428,806		$	1,372,662		$	1,351,755
			Operating Expenses			399,236				382,080			1,229,009			1,222,673
			Operating Income		$	81,118			$	46,726		$	143,653		$	129,082
	(a)	See Note 14 of Notes to Condensed Consolidated Financial Statements for information regarding the Cost Saving Initiatives, and the impact on each of the Company’s business segments during the nine month period ended September 30, 2013.
			As Of
			September 30,				December 31,
			2013				2012
	Total Assets
	Financial Advisory		$	697,183			$	793,007
	Asset Management			632,526				566,677
	Corporate			1,626,747				1,627,209
	Total		$	2,956,456			$	2,986,893

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]
Organization	Organization
	Lazard Ltd, a Bermuda holding company, and its subsidiaries (collectively referred to as “Lazard Ltd”, “Lazard”, “we” or the “Company”), including Lazard Ltd’s indirect investment in Lazard Group LLC, a Delaware limited liability company (collectively referred to, together with its subsidiaries, as “Lazard Group”), is one of the world’s preeminent financial advisory and asset management firms and has long specialized in crafting solutions to the complex financial and strategic challenges of our clients. We serve a diverse set of clients around the world, including corporations, governments, institutions, partnerships and individuals.
	Lazard Ltd indirectly held approximately 99.5% and 98.8% of all outstanding Lazard Group common membership interests as of September 30, 2013 and December 31, 2012, respectively. Lazard Ltd, through its control of the managing members of Lazard Group, controls Lazard Group, which is governed by an Operating Agreement dated as of May 10, 2005, as amended (the “Operating Agreement”). LAZ-MD Holdings LLC (“LAZ-MD Holdings”), an entity owned by Lazard Group’s current and former managing directors, held approximately 0.5% and 1.2% of the outstanding Lazard Group common membership interests as of September 30, 2013 and December 31, 2012, respectively. Additionally, LAZ-MD Holdings was the sole owner of the one issued and outstanding share of Lazard Ltd’s Class B common stock (the “Class B common stock”) which provided LAZ-MD Holdings with approximately 0.5% and 1.2% of the voting power but no economic rights in the Company as of September 30, 2013 and December 31, 2012, respectively. Subject to certain limitations, LAZ-MD Holdings’ interests in Lazard Group are exchangeable for Lazard Ltd Class A common stock, par value $0.01 per share (“Class A common stock”).
	Our sole operating asset is our indirect ownership of common membership interests of Lazard Group and our managing member interest of Lazard Group, whose principal operating activities are included in two business segments:
		•	Financial Advisory, which offers corporate, partnership, institutional, government, sovereign and individual clients across the globe a wide array of financial advisory services regarding mergers and acquisitions (“M&A”) and other strategic matters, restructurings, capital structure, capital raising and various other financial matters, and
		•	Asset Management, which offers a broad range of global investment solutions and investment management services in equity and fixed income strategies, alternative investments and private equity funds to corporations, public funds, sovereign entities, endowments and foundations, labor funds, financial intermediaries and private clients.
	In addition, we record selected other activities in our Corporate segment, including management of cash, investments and outstanding indebtedness, as well as certain commercial banking activities of Lazard Group’s Paris-based subsidiary, Lazard Frères Banque SA (“LFB”).
	LFB is a registered bank regulated by the Autorité de Contrôle Prudentiel et de Résolution (“ACPR”). It is engaged primarily in commercial and private banking services for clients and funds managed by Lazard Frères Gestion SAS (“LFG”) and other clients, investment banking activities, including participation in underwritten offerings of securities in France, and asset-liability management.
Basis of Presentation	Basis of Presentation
	The accompanying condensed consolidated financial statements of Lazard Ltd have been prepared pursuant to the rules and regulations of the United States Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Accordingly, they do not include all of the information and notes required by accounting principles generally accepted in the United States of America (“U.S. GAAP”) for complete financial statements and should be read in conjunction with the audited consolidated financial statements and notes thereto included in Lazard Ltd’s Annual Report on Form 10-K for the year ended December 31, 2012 (the “Form 10-K”). The accompanying December 31, 2012 unaudited condensed consolidated statement of financial condition data was derived from audited consolidated financial statements, but does not include all disclosures required by U.S. GAAP for annual financial statement purposes. The accompanying condensed consolidated financial statements reflect all adjustments which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods presented.
	Preparing financial statements requires management to make estimates and assumptions that affect the amounts that are reported in the financial statements and the accompanying disclosures. Discretionary compensation and benefits expense for interim periods is accrued based on the year-to-date amount of revenue earned, and an assumed annual ratio of compensation and benefits expense to revenue, with the applicable amounts adjusted for certain items. Although these estimates are based on management’s knowledge of current events and actions that Lazard may undertake in the future, actual results may differ materially from the estimates.
	The consolidated results of operations for the three month and nine month periods ended September 30, 2013 are not necessarily indicative of the results to be expected for any future interim or annual period.
	The condensed consolidated financial statements include Lazard Ltd, Lazard Group and Lazard Group’s principal operating subsidiaries: Lazard Frères & Co. LLC (“LFNY”), a New York limited liability company, along with its subsidiaries, including Lazard Asset Management LLC and its subsidiaries (collectively referred to as “LAM”); the French limited liability companies Compagnie Financière Lazard Frères SAS (“CFLF”) along with its subsidiaries, LFB and LFG, and Maison Lazard SAS and its subsidiaries; and Lazard & Co., Limited (“LCL”), through Lazard & Co., Holdings Limited (“LCH”), an English private limited company, together with their jointly owned affiliates and subsidiaries.
	The Company’s policy is to consolidate (i) entities in which it has a controlling financial interest, (ii) variable interest entities (“VIEs”) where the Company has a variable interest and is deemed to be the primary beneficiary and (iii) limited partnerships where the Company is the general partner, unless the presumption of control is overcome. When the Company does not have a controlling interest in an entity, but exerts significant influence over such entity’s operating and financial decisions, the Company applies the equity method of accounting in which it records in earnings its share of earnings or losses of the entity. Intercompany transactions and balances have been eliminated.
Offsetting (Netting) Assets and Liabilities	Offsetting (Netting) Assets and Liabilities—In the first quarter of 2013, the Company adopted the new disclosure requirements issued by the Financial Accounting Standards Board (the “FASB”) regarding the nature of an entity’s rights of setoff and related arrangements associated with its financial instruments, including derivatives, repurchase agreements and reverse repurchase agreements and securities borrowing and securities lending transactions that are either (i) offset or (ii) subject to an enforceable master netting arrangement. The new disclosures are designed to make financial statements prepared under U.S. GAAP more comparable to those prepared under International Financial Reporting Standards (“IFRS”) and will enable users of an entity’s financial statements to evaluate the effect or potential effect of netting arrangements on an entity’s financial position. The disclosure requirements are effective for interim and annual reporting periods beginning on or after January 1, 2013, with retrospective application required. The adoption of the new disclosure requirements did not have a material impact on the Company’s consolidated financial statements.
Reclassifications out of Accumulated Other Comprehensive Income	Reclassifications Out of Accumulated Other Comprehensive Income—In the first quarter of 2013, the Company adopted the FASB’s amended guidance regarding the presentation of amounts reclassified out of accumulated other comprehensive income. The amendment required that the amounts reclassified out of accumulated other comprehensive income be presented by component and disclosed where the respective line item was reported in the consolidated statement of operations. The amendment was to be applied prospectively, and is effective with interim and annual periods beginning after December 15, 2012, with early adoption permitted. The adoption of the amended guidance did not have a material impact on the Company’s consolidated financial statements.
Presentation of Unrecognized Tax Benefits	Presentation of Unrecognized Tax Benefits—In July 2013, the FASB issued guidance on the presentation of unrecognized tax benefits when net operating losses or tax credit carryforwards exist. The guidance requires that the unrecognized tax benefit, or a portion of such unrecognized tax benefit, be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except in certain situations, as defined in the guidance. The new presentation requirements are effective prospectively for interim and annual reporting periods beginning after December 15, 2013. The Company is currently evaluating this guidance, but does not anticipate its adoption will have a material impact on the Company’s consolidated financial statements.

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2013
Investments Schedule [Abstract]
Company's Investments and Securities Sold, Not Yet Purchased	The Company’s investments and securities sold, not yet purchased, consisted of the following at September 30, 2013 and December 31, 2012:
			September 30,		December 31,
			2013		2012
	Debt (including interest-bearing deposits of $519 and $578, respectively)		$	7,501	$	5,948
	Equities			55,467		44,992
	Funds:
	Alternative investments (a)			45,809		57,890
	Debt (a)			58,605		32,077
	Equity (a)			177,831		154,310
	Private equity			115,568		112,444
				397,813		356,721
	Equity method			8,941		7,012
	Total investments			469,722		414,673
	Less:
	Interest-bearing deposits			519		578
	Equity method			8,941		7,012
	Investments, at fair value		$	460,262	$	407,083
	Securities sold, not yet purchased, at fair value (included in “other liabilities”)		$	4,075	$	2,755
	(a)	Interests in alternative investment funds, debt funds and equity funds include investments with fair values of $7,886, $31,029 and $125,571, respectively, at September 30, 2013 and $5,054, $18,615 and $76,907, respectively, at December 31, 2012, held in order to satisfy the Company’s liability upon vesting of previously granted Lazard Fund Interests (“Lazard Fund Interests”) and other similar deferred compensation arrangements. Lazard Fund Interests represent grants by the Company to eligible employees of actual or notional interests in a number of Lazard-managed funds (see Notes 6 and 12 of Notes to Condensed Consolidated Financial Statements).
Schedule of Trading Securities Gross Unrealized Investment Gains and Losses	During the three month and nine month periods ended September 30, 2013 and 2012, the Company reported in revenue-other on its condensed consolidated statements of operations gross unrealized investment gains and losses pertaining to “trading” securities as follows (including, for the three month and nine month periods ended September 30, 2012, restated amounts pertaining to certain non-broker dealer subsidiaries):
			Three Month Period				Nine Month Period
			Ended September 30,				Ended September 30,
			2013		2012		2013		2012
	Gross unrealized investment gains		$	10,925	$	11,825	$	12,044	$	19,137
	Gross unrealized investment losses		$	–	$	–	$	3,907	$	35

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Classification of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables present the classification of investments and certain other assets and liabilities measured at fair value on a recurring basis as of September 30, 2013 and December 31, 2012 within the fair value hierarchy:
			30-Sep-13
			Level 1		Level 2			Level 3			Total
	Assets:
	Investments:
	Debt (excluding interest-bearing deposits)		$	1,090	$	5,892		$	–		$	6,982
	Equities			54,144		–			1,323			55,467
	Funds:
	Alternative investments			–		45,809			–			45,809
	Debt			58,601		4			–			58,605
	Equity			177,792		39			–			177,831
	Private equity			–		–			115,568			115,568
	Derivatives			–		313			–			313
	Total		$	291,627	$	52,057		$	116,891		$	460,575
	Liabilities:
	Securities sold, not yet purchased		$	4,075	$	–		$	–		$	4,075
	Derivatives			–		159,267			–			159,267
	Total		$	4,075	$	159,267		$	–		$	163,342
			31-Dec-12
			Level 1		Level 2			Level 3			Total
	Assets:
	Investments:
	Debt (excluding interest-bearing deposits)		$	1,443	$	3,927		$	–		$	5,370
	Equities			44,802		–			190			44,992
	Funds:
	Alternative investments			–		54,433			3,457			57,890
	Debt			32,073		4			–			32,077
	Equity			145,231		9,069			10			154,310
	Private equity			–		–			112,444			112,444
	Derivatives			–		933			–			933
	Total		$	223,549	$	68,366		$	116,101		$	408,016
	Liabilities:
	Securities sold, not yet purchased		$	2,696	$	59		$	–		$	2,755
	Derivatives			–		102,492			–			102,492
	Total		$	2,696	$	102,551		$	–		$	105,247
Summary of Changes in Fair Value of Company's Level 3 Assets	The following tables provide a summary of changes in fair value of the Company’s Level 3 assets for the three month and nine month periods ended September 30, 2013 and 2012:
			Three Months Ended September 30, 2013
			Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
			Balance		Realized			Acquisitions			Dispositions			Currency			Balance
					Gains (Losses)									Translation
					Included									Adjustments
					In Revenue-
					Other (a)
	Investments:
	Equities		$	637	$	2		$	650		$	–		$	34		$	1,323
	Alternative investment funds			11		(11	)		–			–			–			–
	Private equity funds			112,833		5,174			2,907			-6,848			1,502			115,568
	Total Level 3 Assets		$	113,481	$	5,165		$	3,557		$	-6,848		$	1,536		$	116,891
			Nine Months Ended September 30, 2013
			Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
			Balance		Realized			Acquisitions			Dispositions			Currency			Balance
					Gains (Losses)									Translation
					Included									Adjustments
					In Revenue-
					Other (a)
	Investments:
	Equities		$	190	$	8		$	1,095		$	–			$  30		$	1,323
	Alternative investment funds			3,457		117			–			(3,574	)		–			–
	Equity funds			10		–			–			(10	)		–			–
	Private equity funds			112,444		8,912			6,166			(12,716	)		762			115,568
	Total Level 3 Assets		$	116,101	$	9,037		$	7,261		$	(16,300	)		$792		$	116,891
			Three Months Ended September 30, 2012
			Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
			Balance		Realized			Acquisitions			Dispositions			Currency			Balance
					Gains (Losses)									Translation
					Included									Adjustments
					In Revenue-
					Other (a)
	Investments:
	Equities		$	181	$	–		$	–		$	–		$	5		$	186
	Alternative investment funds			4,626		18			10			(1,209	)		–			3,445
	Private equity funds			113,991		(522	)		2,945			(348	)		1,128			117,194
	Total Level 3 Assets		$	118,798	$	(504	)	$	2,955		$	(1,557	)	$	1,133		$	120,825
			Nine Months Ended September 30, 2012
			Beginning		Net  Unrealized/			Purchases/			Sales/			Foreign			Ending
			Balance		Realized			Acquisitions			Dispositions			Currency			Balance
					Gains (Losses)									Translation
					Included									Adjustments
					In Revenue-
					Other (a)
	Investments:
	Equities		$	211	$	5		$	–		$	(30	)	$	–		$	186
	Alternative investment funds			10,171		107			20			(6,853	)		–			3,445
	Private equity funds			122,718		11,828			5,697			(23,093	)		44			117,194
	Total Level 3 Assets		$	133,100	$	11,940		$	5,717		$	(29,976	)	$	44		$	120,825
	(a)	Earnings for the three month and nine month periods ended September 30, 2013 and the three month and nine month periods ended September 30, 2012 include net unrealized gains (losses) of $2,680, $6,007, $(460) and $9,103, respectively.
Fair Value of Certain Investments Based on NAV	Fair Value of Certain Investments Based on NAV—The Company’s Level 2 and Level 3 investments at September 30, 2013 and December 31, 2012 include certain investments that are valued using NAV or its equivalent as a practical expedient in determining fair value. Information with respect thereto was as follows:
			30-Sep-13
								% of		Estimated Liquidation Period of				Investments Redeemable
								Fair Value		Investments Not Redeemable
								Not
			Fair Value		Unfunded			Redeemable		%	%		%	Redemption		Redemption
					Commitments					Next	10-May		Thereafter	Frequency		Notice Period
										5 Years	Years
	Alternative investment funds		$	45,809	$	–		NA		NA	NA		NA	(a)		<30-90 days
	Debt funds			4		–		NA		NA	NA		NA	(b)		30 days
	Equity funds			39		–		NA		NA	NA		NA	(c)		<30-90 days
	Private equity funds			115,568		27,685		100%		13%	36%		51%	NA		NA
	Total		$	161,420	$	27,685
	Redemption frequency as follows:
	(a)	daily (1%), weekly (12%), monthly (55%) and quarterly (32%)
	(b)	daily (100%)
	(c)	daily (13%), monthly (58%) and quarterly (29%)
			31-Dec-12
								% of		Estimated Liquidation Period of				Investments Redeemable
								Fair Value		Investments Not Redeemable
								Not
			Fair Value		Unfunded			Redeemable		%	%		%	Redemption		Redemption
					Commitments					Next	10-May		Thereafter	Frequency		Notice Period
										5 Years	Years
	Alternative investment funds		$	57,890	$	–		NA		NA	NA		NA	(a)		<30-120 days
	Debt funds			4		–		NA		NA	NA		NA	(b)		30 days
	Equity funds			9,079		–		2%		–%	–%		2%	(c)		30-120 days
	Private equity funds			112,444		31,482		100%		13%	39%		48%	NA		NA
	Total		$	179,417	$	31,482
	Redemption frequency as follows:
	(a)	daily (10%), weekly (9%), monthly (38%) and quarterly (43%)
	(b)	daily (100%)
	(c)	daily (37%) and monthly (61%)

Derivatives_Tables

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Fair Value of Derivatives Reported on Consolidated Statements of Financial Condition	The tables below present the fair values of the Company’s derivative instruments reported within “other assets” and “other liabilities” and the fair values of the Company’s derivative liabilities relating to its obligations pertaining to Lazard Fund Interests and other similar deferred compensation arrangements (see Note 12 of Notes to Condensed Consolidated Financial Statements) on the accompanying condensed consolidated statements of financial condition as of September 30, 2013 and December 31, 2012:
			September 30,			December 31,
			2013			2012
	Derivative Assets:
	Forward foreign currency exchange rate contracts		$	313		$	893
	Equity and fixed income swaps and other (a)			–			40
			$	313		$	933
	Derivative Liabilities:
	Forward foreign currency exchange rate contracts		$	1,136		$	322
	Interest rate swaps			–			235
	Equity and fixed income swaps (a)			1,825			4,342
	Lazard Fund Interests and other similar deferred compensation arrangements			156,306			97,593
			$	159,267		$	102,492
	(a)	For equity and fixed income swaps, amounts represent the netting of gross derivative assets and liabilities of $480 and $2,305 as of September 30, 2013, respectively, and $0 and $4,342 as of December 31, 2012, respectively, for contracts with the same counterparty under legally enforceable master netting agreements. Such amounts are recorded “net” in “other assets”, with receivables for net cash collateral under such contracts of $14,684 and $15,304 as of September 30, 2013 and December 31, 2012, respectively.
Net Gains (Losses) with Respect to Derivative Instruments Not Designated as Hedging Instruments	Net gains (losses) with respect to derivative instruments (predominantly reflected in “revenue-other”) and the Company’s derivative liabilities relating to its obligations pertaining to Lazard Fund Interests and other similar deferred compensation arrangements (included in “compensation and benefits” expense) as reflected on the accompanying condensed consolidated statements of operations for the three month and nine month periods ended September 30, 2013 and 2012, were as follows:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2013			2012			2013			2012
	Forward foreign currency exchange rate contracts		$	(5,310	)	$	(3,377	)	$	(1,705	)	$	(1,248	)
	Lazard Fund Interests and other similar deferred compensation arrangements			(7,519	)		(4,728	)		(7,767	)		(4,639	)
	Equity and fixed income swaps and other			(6,520	)		(7,471	)		(6,872	)		(14,096	)
	Total		$	(19,349	)	$	(15,576	)	$	(16,344	)	$	(19,983	)

Property_Tables

Property (Tables)	9 Months Ended
	Sep. 30, 2013
Property Plant And Equipment [Abstract]
Property-Net	At September 30, 2013 and December 31, 2012, property consisted of the following:
		Estimated		September 30,		December 31,
		Depreciable		2013		2012
		Life in Years
	Buildings		33		$170,479		$166,560
	Leasehold improvements		20-Mar		173,303		143,408
	Furniture and equipment		10-Mar		146,504		122,125
	Construction in progress				4,128		18,801
	Total				494,414		450,894
	Less - accumulated depreciation and amortization				244,634		225,861
	Property				$249,780		$225,033

Goodwill_and_Other_Intangible_1

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Components of Goodwill and Other Intangible Assets	The components of goodwill and other intangible assets at September 30, 2013 and December 31, 2012 are presented below:
			September 30,			December 31,
			2013			2012
	Goodwill		$	350,619		$	364,328
	Other intangible assets (net of accumulated amortization)			25,782			28,494
			$	376,401		$	392,822
Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill for the nine month periods ended September 30, 2013 and 2012 are as follows:
			Nine Months Ended
			September 30,
			2013			2012
	Balance, January 1		$	364,328		$	356,657
	Business acquisitions			1,601			4,272
	Foreign currency translation adjustments			(15,310	)		3,832
	Balance, September 30		$	350,619		$	364,761
Gross Cost and Accumulated Amortization of Other Intangible Assets	The gross cost and accumulated amortization of other intangible assets as of September 30, 2013 and December 31, 2012, by major intangible asset category, are as follows:
			September 30, 2013							31-Dec-12
			Gross Cost			Accumulated		Net Carrying		Gross Cost		Accumulated		Net Carrying
						Amortization		Amount				Amortization		Amount
	Success/performance fees		$	30,740		$	10,726	$	20,014	$	30,740	$	10,678	$	20,062
	Management fees, customer relationships and non-compete agreements			33,081			27,313		5,768		33,035		24,603		8,432
			$	63,821		$	38,039	$	25,782	$	63,775	$	35,281	$	28,494
Estimated Future Amortization Expense	Amortization expense of intangible assets for the three month and nine month periods ended September 30, 2013 was $877 and $2,758, respectively, and for the three month and nine month periods ended September 30, 2012 was $2,494 and $6,172, respectively. Estimated future amortization expense is as follows:
	Year Ending December 31,		Amortization
			Expense (a)
	2013 (October 1 through December 31)		$	2,589
	2014			11,574
	2015			6,438
	2016			5,181
	Total amortization expense		$	25,782
		(a)	Approximately 45% of intangible asset amortization is attributable to a noncontrolling interest.

Senior_Debt_Tables

Senior Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]
Senior Debt	Senior debt was comprised of the following as of September 30, 2013 and December 31, 2012:
		Initial		Maturity		Annual			Outstanding As Of
		Principal		Date		Interest
		Amount				Rate			September 30,		December 31,
									2013		2012
	Lazard Group 7.125% Senior Notes	$	550,000		5/15/15		7.125	%	$	528,500	$	528,500
	Lazard Group 6.85% Senior Notes		600,000		6/15/17		6.85	%		548,350		548,350
	Lazard Group Credit Facility		150,000		9/25/15		0.76	%		–		–
	Total								$	1,076,850	$	1,076,850

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]
Lazard Group Distributed Amounts to LAZ-MD Holdings and Subsidiaries of Lazard Ltd	During the nine month periods ended September 30, 2013 and 2012, Lazard Group distributed the following amounts to LAZ-MD Holdings and the subsidiaries of Lazard Ltd (none of which related to tax distributions):
			Nine Months Ended
			September 30,
			2013			2012
	LAZ-MD Holdings		$	565		$	3,729
	Subsidiaries of Lazard Ltd			60,931			66,219
			$	61,496		$	69,948
Accumulated Other Comprehensive Income (Loss), Net of Tax	Accumulated Other Comprehensive Income (Loss), Net of Tax (“AOCI”)—The table below reflects the components of AOCI at September 30, 2013 and activity during the nine month period then ended:
			Currency			Interest			Employee			Total				Amount			Total
			Translation			Rate			Benefit			AOCI				Attributable to			Lazard Ltd
			Adjustments			Hedge			Plans							Noncontrolling			AOCI
																Interests
	Balance, January 1, 2013		$	19,405		$	(2,502	)	$	(128,536	)	$	(111,633	)		$	(1,092	)	$	(110,541	)
	Activity January 1 to September 30, 2013:
	Other comprehensive gain (loss) before reclassifications			(18,610	)		–			(2,669	)		(21,279	)			451			(21,730	)
	Adjustments for items reclassified to earnings, net of tax			–			791			3,653			4,444				25			4,419
	Net other comprehensive			(18,610	)		791			984			(16,835	)			476			(17,311	)
	income (loss)
	Balance, September 30, 2013		$	795		$	(1,711	)	$	(127,552	)	$	(128,468	)		$	(616	)	$	(127,852	)
Gains (Losses) Reclassified Out of AOCI	The table below reflects adjustments for items reclassified out of AOCI, by component, for the three month and nine month periods ended September 30, 2013:
			Three Months Ended			Nine Months Ended
			September 30,			September 30,
			2013			2013
	Amortization of interest rate hedge		$	264	(a)	$	791	(a)
	Amortization relating to employee benefit plans			1,627	(b)		4,859	(b)
	Less - related income taxes			404			1,206
	Net of tax			1,223			3,653
	Total reclassifications, net of tax		$	1,487		$	4,444
	(a)	Included in “interest expense” on the condensed consolidated statements of operations.
	(b)	Included in the computation of net periodic benefit cost (see Note 13 of Notes to Condensed Consolidated Financial Statements). Such amount is included in “compensation and benefits” expense on the condensed consolidated statement of operations.
Changes in Ownership Interests	The following tables summarize the changes in ownership interests in Lazard Group held by Lazard Ltd and LAZ-MD Holdings during the nine month periods ended September 30, 2013 and 2012:
			Lazard Ltd						LAZ-MD Holdings					Total
														Lazard
														Group
														Common
														Membership
			Common			%			Common			%		Interests
			Membership			Ownership			Membership			Ownership
			Interests						Interests
	Balance, January 1, 2012			123,009,311			94.80%			6,756,779		5.20%			129,766,090
	Activity January 1, 2012 to September 30, 2012:
	Common membership interest activity in connection with:
	Exchanges for Class A common stock			191,701						(191,701	)				–
	Balance, September 30, 2012			123,201,012			94.9	%		6,565,078		5.10%			129,766,090
	Balance, January 1, 2013			128,216,423			98.8	%		1,549,667		1.20%			129,766,090
	Activity January 1, 2013 to September 30, 2013:
	Common membership interest activity in connection with:
	Exchanges for Class A common stock			839,658						(839,658	)				–
	Balance, September 30, 2013			129,056,081			99.5	%		710,009		0.50%			129,766,090
Net Income Attributable to Noncontrolling Interests	The tables below summarize net income attributable to noncontrolling interests for the three month and nine month periods ended September 30, 2013 and 2012 and noncontrolling interests as of September 30, 2013 and December 31, 2012 in the Company’s condensed consolidated financial statements:
			Net Income (Loss) Attributable To
			Noncontrolling Interests
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2013			2012			2013			2012
	Edgewater		$	2,018		$	(1,704	)	$	4,671		$	2,168
	LAZ-MD Holdings			365			1,937			862			4,956
	Other			83			139			(210	)		93
	Total		$	2,466		$	372		$	5,323		$	7,217
			Noncontrolling Interests As Of
			September 30,			December 31,
			2013			2012
	Edgewater		$	71,075		$	75,262
	LAZ-MD Holdings			2,629			5,405
	Other			583			1,217
	Total		$	74,287		$	81,884

Incentive_Plans_Tables

Incentive Plans (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense	The following reflects the amortization expense recorded with respect to share-based incentive plans within “compensation and benefits” expense (with respect to RSUs, PRSUs and restricted stock awards) and “professional services” expense (with respect to deferred stock units (“DSUs”)) within the Company’s accompanying condensed consolidated statements of operations:
			Three Months  Ended							Nine Months Ended
			September 30,							September 30,
			2013			2012				2013		2012
	Share-based incentive awards:
	RSUs (a)		$	46,095		$	65,952			$	163,184	$	211,271
	PRSUs			6,467			–				8,900		–
	Restricted stock (b)			2,627			1,659				9,712		7,538
	DSUs			71			78				1,545		1,366
	Total		$	55,260		$	67,689			$	183,341	$	220,175
	(a)	Includes $0 and $9,099 during the three month and nine month periods ended September 30, 2013 relating to the Cost Saving Initiatives (see Note 14 of Notes to Condensed Consolidated Financial Statements).
	(b)	Includes $0 and $247 during the three month and nine month periods ended September 30, 2013 relating to the Cost Saving Initiatives.
Schedule of Issuance of RSUs and Charges to Retained Earnings	During the nine month periods ended September 30, 2013 and 2012, issuances of RSUs pertaining to such dividend participation rights and respective charges to “retained earnings”, net of estimated forfeitures (with corresponding credits to “additional paid-in-capital”), consisted of the following:
			Nine Months  Ended
			September 30,
			2013				2012
	Number of RSUs issued				250,834				479,958
	Charges to retained earnings, net of estimated forfeitures			$	8,216			$	11,770
Schedule of Activity Relating to RSUs and DSUs	The following is a summary of activity relating to RSUs and DSUs during the nine month periods ended September 30, 2013 and 2012:
			RSUs							DSUs
			Units			Weighted				Units		Weighted
						Average						Average
						Grant Date						Grant Date
						Fair Value						Fair Value
	Balance, January 1, 2013			21,481,131		$	33.92				204,496	$	31.47
	Granted (including 250,834 RSUs relating to dividend participation)			4,862,379		$	36.92				45,195	$	34.18
	Forfeited			(239,117	)	$	34.63				–		–
	Vested			(9,363,792	)	$	34.78				–		–
	Balance, September 30, 2013			16,740,601		$	34.3				249,691	$	31.96
	Balance, January 1, 2012			20,751,829		$	36.84				140,660	$	34.83
	Granted (including 479,958 RSUs relating to dividend participation)			8,121,632		$	27.56				57,970	$	23.57
	Forfeited			(401,065	)	$	35.49				–		–
	Vested			(4,425,534	)	$	34.43				–		–
	Balance, September 30, 2012			24,046,862		$	34.16				198,630	$	31.54
Summary of Activity Related to Shares of Restricted Class A Common Stock	The following is a summary of activity related to shares of restricted Class A common stock associated with compensation arrangements during the nine month periods ended September 30, 2013 and 2012:
			Restricted			Weighted
			Shares			Average
						Grant Date
						Fair Value
	Balance, January 1, 2013			1,972,609		$	34.85
	Granted			368,736		$	36.74
	Forfeited			(35,794	)	$	33.35
	Vested			(1,728,509	)	$	36
	Balance, September 30, 2013			577,042		$	32.72
	Balance, January 1, 2012			95,332		$	37.63
	Granted/Exchanged			577,323		$	29.25
	Forfeited			(21,178	)	$	29.51
	Vested			(186,180	)	$	31.6
	Balance, September 30, 2012			465,297		$	30.02
Summary of Fund Interests and Other Similar Deferred Compensation Arrangements	The following is a summary of activity relating to Lazard Fund Interests and other similar deferred compensation arrangements during the nine month periods ended September 30, 2013 and 2012:
			Prepaid			Compensation
			Compensation			Liability
			Asset
	Balance, January 1, 2013		$	47,445		$	97,593
	Granted			72,217			72,217
	Settled			–			(22,903	)
	Forfeited			(765	)		(985	)
	Amortization			(44,195	)		–
	Change in fair value related to:
	Increase in fair value of underlying investments			–			7,767
	Adjustment for estimated forfeitures			–			3,175
	Other			(217	)		(558	)
	Balance, September 30, 2013		$	74,485		$	156,306
			Prepaid			Compensation
			Compensation			Liability
			Asset
	Balance, January 1, 2012		$	17,782		$	29,900
	Granted			64,658			64,658
	Settled			–			(8,640	)
	Forfeited			(1,607	)		(1,706	)
	Amortization			(24,508	)		–
	Change in fair value related to:
	Increase in fair value of underlying investments			–			4,639
	Adjustment for estimated forfeitures			–			2,202
	Other			101			–
	Balance, September 30, 2012		$	56,426		$	91,053
Summary of Impact of Fund Interests and Other Similar Deferred Compensation Arrangements	The following is a summary of the impact of Lazard Fund Interests and other similar deferred compensation arrangements on “compensation and benefits” expense within the accompanying condensed consolidated statements of operations for the three month and nine month periods ended September 30, 2013 and 2012:
			Three Months Ended							Nine Months Ended
			September 30,							September 30,
			2013			2012				2013		2012
	Compensation expense:
	Amortization, net of forfeitures (a)		$	15,049		$	9,626			$	47,150	$	26,611
	Change in fair value of underlying investments			7,519			4,728				7,767		4,639
	Total		$	22,568		$	14,354			$	54,917	$	31,250
	(a)	Includes $0 and $2,665 during the three month and nine month periods ended September 30, 2013 relating to the Cost Saving Initiatives.

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2013
Compensation And Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost	The following table summarizes the components of net periodic benefit cost related to the Company’s post-retirement plans for the three month and nine month periods ended September 30, 2013 and 2012:
			Pension Plans						Medical Plan
			Three Months Ended September 30,
			2013			2012			2013		2012
	Components of Net Benefit Cost (Credit):
	Service cost		$	315		$	166		$	12	$	15
	Interest cost			6,744			6,862			46		53
	Expected return on plan assets			(6,701	)		(6,637	)		–		–
	Amortization of:
	Prior service cost			708			668			–		–
	Net actuarial loss			919			412			–		–
	Net benefit cost		$	1,985		$	1,471		$	58	$	68
			Pension Plans						Medical Plan
			Nine Months Ended September 30,
			2013			2012			2013		2012
	Components of Net Benefit Cost (Credit):
	Service cost		$	938		$	504		$	39	$	45
	Interest cost			20,193			20,649			137		158
	Expected return on plan assets			(20,090	)		(19,931	)		–		–
	Amortization of:
	Prior service cost			2,114			2,056			–		–
	Net actuarial loss			2,745			1,243			–		–
	Settlement loss (a)			–			886			–		–
	Net benefit cost		$	5,900		$	5,407		$	176	$	203
	(a)	During the nine month period ended September 30, 2012, the Company’s pension plans in the U.S. made lump sum benefit payments in excess of the plans’ annual service and interest costs, which, under U.S. GAAP, requires that the plans’ obligations and assets be remeasured. The remeasurement of the plans resulted in the recognition of actuarial losses totaling $1,935 recorded in “other comprehensive income (loss), net of tax” (“OCI”), which, combined with a settlement loss of $886 recognized in “compensation and benefits” expense, resulted in a net charge to OCI of $1,049.

Cost_Saving_Initiatives_Tables

Cost Saving Initiatives (Tables)	9 Months Ended
	Sep. 30, 2013
Restructuring And Related Activities [Abstract]
Schedule of Expenses and Cumulative Expenses Associated With Implementation of Cost Savings Initiatives	Expenses associated with the implementation of the Cost Saving Initiatives were completed during the second quarter of 2013. The Company incurred these expenses, by segment, as reflected in the tables below:
		Financial			Asset			Corporate			Total
		Advisory			Management
	Nine Month Period Ended September 30, 2013:
	Compensation and benefits	$	45,746		$	236		$	5,417		$	51,399
	Other		2,033			(1	)		11,272			13,304
	Total	$	47,779		$	235		$	16,689		$	64,703
		Financial			Asset			Corporate			Total
		Advisory			Management
	Cumulative October 2012 Through September 30, 2013:
	Compensation and benefits	$	121,879		$	12,292		$	17,215		$	151,386
	Other		3,432			732			11,729			15,893
	Total	$	125,311		$	13,024		$	28,944		$	167,279
Activity Related to Obligations Pursuant to Cost Saving Initiatives	Activity related to the obligations pursuant to the Cost Saving Initiatives during the nine month period ended September 30, 2013 was as follows:
		Accrued			Other			Total
		Compensation			Liabilities
		and Benefits
	Balance, January 1, 2013	$	46,128		$	1,714		$	47,842
	New charges		51,399			13,304			64,703
	Less:
	Non-cash charges		(12,007	)		(3,387	)		(15,394	)
	Settlements		(68,813	)		(2,299	)		(71,112	)
	Balance, September 30, 2013	$	16,707		$	9,332		$	26,039

Net_Income_Per_Share_of_Class_1

Net Income Per Share of Class A Common Stock (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]
Company's Basic and Diluted Net Income Per Share and Weighted Average Shares Outstanding	The calculations of the Company’s basic and diluted net income per share and weighted average shares outstanding for the three month and nine month periods ended September 30, 2013 and 2012 are presented below:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
	Net income attributable to Lazard Ltd	$	60,282		$33,301		$106,995		$89,674
	Add - adjustment associated with Class A common stock issuable on a non-contingent basis		–		3		–		6
	Net income attributable to Lazard Ltd - basic		60,282		33,304		106,995		89,680
	Add - dilutive effect, as applicable, of:
	Adjustments to income relating to interest expense and changes in net income attributable to noncontrolling interests resulting from assumed Class A common stock issuances in connection with share-based incentive compensation and exchangeable interests, net of tax		316		1,804		787		4,680
	Net income attributable to Lazard Ltd - diluted		$60,598		$35,108		$107,782		$94,360
	Weighted average number of shares of Class A common stock outstanding		121,441,956		114,689,712		119,797,545		116,949,317
	Add - adjustment for shares of Class A common stock issuable on a non-contingent basis		757,998		913,639		758,502		740,087
	Weighted average number of shares of Class A common stock outstanding - basic		122,199,954		115,603,351		120,556,047		117,689,404
	Add - dilutive effect, as applicable, of:
	Weighted average number of incremental shares of Class A common stock issuable from share-based incentive compensation and exchangeable interests		12,042,190		19,776,685		12,617,953		17,847,646
	Weighted average number of shares of Class A common stock outstanding - diluted		134,242,144		135,380,036		133,174,000		135,537,050
	Net income attributable to Lazard Ltd per share of Class A common stock:
	Basic		$0.49		$0.29		$0.89		$0.76
	Diluted		$0.45		$0.26		$0.81		$0.70

Related_Parties_Tables

Related Parties (Tables)	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]
Amounts Receivable from and Payable to Related Parties	Amounts receivable from, and payable to, related parties are set forth below:
		September  30,		December 31,
		2013		2012
	Receivables
	LFCM Holdings	$	13,015	$	20,529
	Other		1,261		3,272
	Total	$	14,276	$	23,801
	Payables
	LFCM Holdings	$	4,335	$	2,943
	Other		360		705
	Total	$	4,695	$	3,648

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]
Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets	the following information provides a reasonable representation of each segment’s contribution with respect to net revenue, operating income (loss) and total assets:
					Three Months Ended							Nine Months Ended
					September 30,							September 30,
					2013				2012			2013(a)			2012
	Financial Advisory		Net Revenue		$	233,842			$	219,973		$	665,611		$	739,793
			Operating Expenses			218,015				212,449			674,689			693,546
			Operating Income (Loss)		$	15,827			$	7,524		$	(9,078	)	$	46,247
	Asset Management		Net Revenue		$	252,094			$	221,516		$	741,618		$	647,096
			Operating Expenses			168,895				160,869			511,526			477,989
			Operating Income		$	83,199			$	60,647		$	230,092		$	169,107
	Corporate		Net Revenue (Expense)		$	(5,582	)		$	(12,683	)	$	(34,567	)	$	(35,134	)
			Operating Expenses			12,326				8,762			42,794			51,138
			Operating Income (Loss)		$	(17,908	)		$	(21,445	)	$	(77,361	)	$	(86,272	)
	Total		Net Revenue		$	480,354			$	428,806		$	1,372,662		$	1,351,755
			Operating Expenses			399,236				382,080			1,229,009			1,222,673
			Operating Income		$	81,118			$	46,726		$	143,653		$	129,082
	(a)	See Note 14 of Notes to Condensed Consolidated Financial Statements for information regarding the Cost Saving Initiatives, and the impact on each of the Company’s business segments during the nine month period ended September 30, 2013.
			As Of
			September 30,				December 31,
			2013				2012
	Total Assets
	Financial Advisory		$	697,183			$	793,007
	Asset Management			632,526				566,677
	Corporate			1,626,747				1,627,209
	Total		$	2,956,456			$	2,986,893

Organization_and_Basis_of_Pres2

Organization and Basis of Presentation - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012
	Segment	Class B Common Stock [Member]	Class B Common Stock [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]	Lazard Ltd [Member]	Lazard Ltd [Member]	LAZ-MD Holdings LLC [Member]	LAZ-MD Holdings LLC [Member]	LAZ-MD Holdings LLC [Member]	LAZ-MD Holdings LLC [Member]
										Class B Common Stock [Member]	Class B Common Stock [Member]
Organization And Basis Of Presentation [Line Items]
Percentage of common membership interests held						99.50%	98.80%	0.50%	1.20%
Governing Operating Agreement, date	10-May-05
Common membership voting power held										0.50%	1.20%
Common stock, par value		$0.01	$0.01	$0.01	$0.01
Common stock, shares outstanding		1	1	129,056,081	128,216,423					1
Common stock, shares issued		1	1	129,056,081	128,216,423					1
Number of business segments	2

Receivables_Additional_Informa

Receivables - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Receivables, Net [Line Items]
Allowance for doubtful accounts receivables	$26,160		$26,160		$23,017
Bad debt expense, (recoveries)	-198	1,553	1,644	2,701
Charge-offs, foreign currency translation and other adjustments	1,765	15	1,499	173
Interest-bearing financing fee receivables	58,531		58,531		76,481
Aggregate carrying amount of non-interest bearing receivables	477,620		477,620		401,562
Trade Receivables [Member]
Receivables, Net [Line Items]
Allowance for doubtful accounts receivables	26,160		26,160		23,017
Receivables past due or deemed uncollectible	36,255		36,255		25,604
Financing Receivables [Member]
Receivables, Net [Line Items]
Allowance for doubtful accounts receivables	$0		$0		$0

Investments_Companys_Investmen

Investments - Company's Investments and Securities Sold, Not Yet Purchased (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Debt (including interest-bearing deposits of $519 and $578, respectively)	$7,501	$5,948
Equities	55,467	44,992
Funds	397,813	356,721
Equity method	8,941	7,012
Total investments	469,722	414,673
Interest-bearing deposits	519	578
Investments, at fair value	460,262	407,083
Securities sold, not yet purchased, at fair value (included in "other liabilities")	4,075	2,755
Debt Funds [Member]
Schedule of Investments [Line Items]
Funds	58,605	32,077
Alternative Investments Funds [Member]
Schedule of Investments [Line Items]
Funds	45,809	57,890
Equity Funds [Member]
Schedule of Investments [Line Items]
Funds	177,831	154,310
Private Equity Funds [Member]
Schedule of Investments [Line Items]
Funds	$115,568	$112,444

Investments_Companys_Investmen1

Investments - Company's Investments and Securities Sold, Not Yet Purchased (Parenthetical) (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value Disclosures [Abstract]
Interest-bearing deposits	$519	$578
Lazard Fund Interests in equities	125,571	76,907
Lazard Fund Interests in alternative investments	7,886	5,054
Lazard Fund Interests in debt	$31,029	$18,615

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule Of Investments [Abstract]
Economic interests that are owned by management team and other investors in the Edgewater Funds	$12,379	$11,490

Investments_Schedule_of_Tradin

Investments - Schedule of Trading Securities Gross Unrealized Investment Gains and Losses (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Investments Debt And Equity Securities [Abstract]
Gross unrealized investment gains	$10,925	$11,825	$12,044	$19,137
Gross unrealized investment losses			$3,907	$35

Fair_Value_Measurements_Classi

Fair Value Measurements - Classification of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$460,262	$407,083
Equities	55,467	44,992
Derivatives	313	933
Securities sold, not yet purchased	4,075	2,755
Derivatives	159,267	102,492
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equities	55,467	44,992
Derivatives	313	933
Total Assets	460,575	408,016
Securities sold, not yet purchased	4,075	2,755
Derivatives	159,267	102,492
Total Liabilities	163,342	105,247
Debt [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	6,982	5,370
Alternative Investments Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	45,809	57,890
Debt Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	58,605	32,077
Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	177,831	154,310
Private Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	115,568	112,444
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equities	54,144	44,802
Derivatives
Total Assets	291,627	223,549
Securities sold, not yet purchased	4,075	2,696
Derivatives
Total Liabilities	4,075	2,696
Level 1 [Member] | Debt [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,090	1,443
Level 1 [Member] | Alternative Investments Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Level 1 [Member] | Debt Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	58,601	32,073
Level 1 [Member] | Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	177,792	145,231
Level 1 [Member] | Private Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equities
Derivatives	313	933
Total Assets	52,057	68,366
Securities sold, not yet purchased		59
Derivatives	159,267	102,492
Total Liabilities	159,267	102,551
Level 2 [Member] | Debt [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,892	3,927
Level 2 [Member] | Alternative Investments Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	45,809	54,433
Level 2 [Member] | Debt Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4	4
Level 2 [Member] | Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	39	9,069
Level 2 [Member] | Private Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equities	1,323	190
Derivatives
Total Assets	116,891	116,101
Securities sold, not yet purchased
Derivatives
Total Liabilities
Level 3 [Member] | Debt [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Level 3 [Member] | Alternative Investments Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		3,457
Level 3 [Member] | Debt Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments
Level 3 [Member] | Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		10
Level 3 [Member] | Private Equity Funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$115,568	$112,444

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Assets (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value Measurements Summary Of Changes In Fair Value Of Level Three Assets [Line Items]
Beginning Balance	$113,481	$118,798	$116,101	$133,100
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	5,165	-504	9,037	11,940
Purchases/Acquisitions	3,557	2,955	7,261	5,717
Sales/Dispositions	-6,848	-1,557	-16,300	-29,976
Foreign Currency Translation Adjustments	1,536	1,133	792	44
Ending Balance	116,891	120,825	116,891	120,825
Equities [Member]
Fair Value Measurements Summary Of Changes In Fair Value Of Level Three Assets [Line Items]
Beginning Balance	637	181	190	211
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	2		8	5
Purchases/Acquisitions	650		1,095
Sales/Dispositions				-30
Foreign Currency Translation Adjustments	34	5	30
Ending Balance	1,323	186	1,323	186
Alternative Investment Funds [Member]
Fair Value Measurements Summary Of Changes In Fair Value Of Level Three Assets [Line Items]
Beginning Balance	11	4,626	3,457	10,171
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	-11	18	117	107
Purchases/Acquisitions		10		20
Sales/Dispositions		-1,209	-3,574	-6,853
Foreign Currency Translation Adjustments
Ending Balance		3,445		3,445
Equity Funds [Member]
Fair Value Measurements Summary Of Changes In Fair Value Of Level Three Assets [Line Items]
Beginning Balance			10
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other
Purchases/Acquisitions
Sales/Dispositions			-10
Foreign Currency Translation Adjustments
Ending Balance
Private Equity Funds [Member]
Fair Value Measurements Summary Of Changes In Fair Value Of Level Three Assets [Line Items]
Beginning Balance	112,833	113,991	112,444	122,718
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	5,174	-522	8,912	11,828
Purchases/Acquisitions	2,907	2,945	6,166	5,697
Sales/Dispositions	-6,848	-348	-12,716	-23,093
Foreign Currency Translation Adjustments	1,502	1,128	762	44
Ending Balance	$115,568	$117,194	$115,568	$117,194

Fair_Value_Measurements_Summar1

Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Assets (Parenthetical) (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value Disclosures [Abstract]
Net unrealized gains (losses)	$2,680	($460)	$6,007	$9,103

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Value of Certain Investments Based on NAV (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	161,420	179,417
Unfunded Commitments	27,685	31,482
Alternative Investment Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	45,809	57,890
Alternative Investment Funds [Member] | Daily [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	1	10
Alternative Investment Funds [Member] | Weekly [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	12	9
Alternative Investment Funds [Member] | Monthly [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	55	38
Alternative Investment Funds [Member] | Quarterly [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	32	43
Alternative Investment Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period	30 days	30 days
Alternative Investment Funds [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period	90 days	120 days
Debt Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period	30 days	30 days
Fair Value	4	4
Debt Funds [Member] | Daily [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	100	100
Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	39	9,079
% of Fair Value Not Redeemable		2.00%
Estimated Liquidation Period of Investments Not Redeemable, % Thereafter		2.00%
Equity Funds [Member] | Daily [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	13	37
Equity Funds [Member] | Monthly [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	58	61
Equity Funds [Member] | Quarterly [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Frequency, Percentage	29
Equity Funds [Member] | Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period	30 days	30 days
Equity Funds [Member] | Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period	90 days	120 days
Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	115,568	112,444
Unfunded Commitments	27,685	31,482
% of Fair Value Not Redeemable	100.00%	100.00%
Estimated Liquidation Period of Investments Not Redeemable, % Next 5 Years	13.00%	13.00%
Estimated Liquidation Period of Investments Not Redeemable, % 5-10 Years	36.00%	39.00%
Estimated Liquidation Period of Investments Not Redeemable, % Thereafter	51.00%	48.00%

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
In Thousands, unless otherwise specified			Corporate Partners II Limited [Member]	Corporate Partners II Limited [Member]	EGCP III [Member]	EGCP III [Member]	COF2 [Member]	COF2 [Member]
				Maximum [Member]		Maximum [Member]		Maximum [Member]
Fair Value Measurements [Line Items]
Unfunded Commitments	$27,685	$31,482		$1,940		$18,501		$7,244
End of the investment period			25-Feb-17		12-Oct-16		11-Nov-16
Remaining commitments date					12-Oct-23		11-Nov-19

Derivatives_Fair_Value_of_Deri

Derivatives - Fair Value of Derivatives Reported on Consolidated Statements of Financial Condition (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative Assets	$313	$933
Derivative Liabilities	159,267	102,492
Forward Foreign Currency Exchange Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	313	893
Derivative Liabilities	1,136	322
Equity and Fixed Income Swaps and Other [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets		40
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities		235
Equity and Fixed Income Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,825	4,342
Lazard Fund Interests and Other Similar Deferred Compensation Arrangements [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$156,306	$97,593

Derivatives_Fair_Value_of_Deri1

Derivatives - Fair Value of Derivatives Reported on Consolidated Statements of Financial Condition (Parenthetical) (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Gross assets for equity and fixed income swaps	$480	$0
Gross liabilities for equity and fixed income swaps	2,305	4,342
Cash collateral pledged for equity and fixed income swaps	$14,684	$15,304

Derivatives_Net_Gains_Losses_w

Derivatives - Net Gains (Losses) with Respect to Derivative Instruments Not Designated as Hedging Instruments (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedging instruments	($19,349)	($15,576)	($16,344)	($19,983)
Forward Foreign Currency Exchange Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedging instruments	-5,310	-3,377	-1,705	-1,248
Lazard Fund Interests and Other Similar Deferred Compensation Arrangements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedging instruments	-7,519	-4,728	-7,767	-4,639
Equity and Fixed Income Swaps and Other [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedging instruments	($6,520)	($7,471)	($6,872)	($14,096)

Property_PropertyNet_Detail

Property - Property-Net (Detail) (USD $)

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

In Thousands, unless otherwise specified

Buildings [Member]

Buildings [Member]

Leasehold Improvements [Member]

Leasehold Improvements [Member]

Furniture and Equipment [Member]

Furniture and Equipment [Member]

Construction in Progress [Member]

Construction in Progress [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Leasehold Improvements [Member]

Furniture and Equipment [Member]

Buildings [Member]

Leasehold Improvements [Member]

Furniture and Equipment [Member]

Property, Plant and Equipment [Line Items]

Property, Plant and Equipment, Gross

$494,414

$450,894

$170,479

$166,560

$173,303

$143,408

$146,504

$122,125

$4,128

$18,801

Less - accumulated depreciation and amortization

244,634

225,861

Property

$249,780

$225,033

Property, Plant and Equipment, Useful Life

3 years

3 years

33 years

20 years

10 years

Goodwill_and_Other_Intangible_2

Goodwill and Other Intangible Assets - Components of Goodwill and Other Intangible Assets (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	$350,619	$364,328	$364,761	$356,657
Other intangible assets (net of accumulated amortization)	25,782	28,494
Goodwill and other intangible assets, Total	$376,401	$392,822

Goodwill_and_Other_Intangible_3

Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Goodwill And Intangible Assets [Line Items]
Goodwill	$350,619	$364,761	$350,619	$364,761	$364,328	$356,657
Amortization expense of intangible assets	877	2,494	2,758	6,172
Financial Advisory Segment [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	286,078		286,078		299,787
Asset Management Segment [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	$64,541		$64,541		$64,541

Goodwill_and_Other_Intangible_4

Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning Balance	$364,328	$356,657
Business acquisitions	1,601	4,272
Foreign currency translation adjustments	-15,310	3,832
Ending Balance	$350,619	$364,761

Goodwill_and_Other_Intangible_5

Goodwill and Other Intangible Assets - Gross Cost and Accumulated Amortization of Other Intangible Assets (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Intangible Assets [Line Items]
Other intangible assets, Gross Cost	$63,821	$63,775
Other intangible assets, Accumulated Amortization	38,039	35,281
Other intangible assets, Net Carrying Amount	25,782	28,494
Success\Performance Fees [Member]
Intangible Assets [Line Items]
Other intangible assets, Gross Cost	30,740	30,740
Other intangible assets, Accumulated Amortization	10,726	10,678
Other intangible assets, Net Carrying Amount	20,014	20,062
Management Fees, Customer Relationships and Non-Compete Agreements [Member]
Intangible Assets [Line Items]
Other intangible assets, Gross Cost	33,081	33,035
Other intangible assets, Accumulated Amortization	27,313	24,603
Other intangible assets, Net Carrying Amount	$5,768	$8,432

Goodwill_and_Other_Intangible_6

Goodwill and Other Intangible Assets - Estimated Future Amortization Expense (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]
2013	$2,589
2014	11,574
2015	6,438
2016	5,181
Total amortization expense	$25,782

Goodwill_and_Other_Intangible_7

Goodwill and Other Intangible Assets - Estimated Future Amortization Expense (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible asset amortization attributable to noncontrolling interest, percentage	45.00%

Senior_Debt_Senior_Debt_Detail

Senior Debt - Senior Debt (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 25, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified				Lazard Group 7.125% Senior Notes [Member]	Lazard Group 7.125% Senior Notes [Member]	Lazard Group 6.85% Senior Notes [Member]	Lazard Group 6.85% Senior Notes [Member]	Lazard Group Credit Facility [Member]	Lazard Group Credit Facility [Member]
Debt Instrument [Line Items]
Senior Debt, Outstanding	$1,076,850	$1,076,850		$528,500	$528,500	$548,350	$548,350
Revolving Credit Facility, Initial Principal Amount			150,000					150,000
Senior Debt, Maturity Date				15-May-15		15-Jun-17
Credit Facility, Expiration Date								25-Sep-15
Revolving Credit Facility, Annual Interest Rate								0.76%
Senior Debt, Initial Principal Amount				$550,000		$600,000
Senior Debt, Annual Interest Rate				7.13%		6.85%

Senior_Debt_Additional_Informa

Senior Debt - Additional Information (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 25, 2012
Debt Instrument [Line Items]
Senior revolving credit facility over next 3 years			$150,000
Duration of senior revolving credit facility, in years			3 years
Outstanding credit facility	0	0
Unused lines of credit available	264,000
Senior Debt [Member]
Debt Instrument [Line Items]
Fair value of senior debt	1,197,000	1,207,000
Fair value of senior debt in excess of the aggregate carrying amount	120,000	130,000
LFB [Member]
Debt Instrument [Line Items]
Unused lines of credit available	54,000
Edgewater [Member]
Debt Instrument [Line Items]
Unused lines of credit available	$55,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Expiration date of credit facility	25-Sep-15
Revolving credit facility annual interest rate	0.76%

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended	1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Jul. 15, 2009	Sep. 30, 2013	Dec. 31, 2012	Jul. 15, 2009	Jul. 15, 2009	Mar. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013
				Initial Shares [Member]	Shares Issued And Subject To Earnout Criteria [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]
									Maximum [Member]
Contingencies And Commitments [Line Items]
Guarantees indemnifications		$4,337
Collateral/counter-guarantees		3,572
Aggregate fair value of consideration recognized by the company at acquisition date	61,624
Initial shares issued at acquisition				1,142,857	1,142,857
Earnout shares earned		1,371,992	1,209,154
Earnout shares became settled		0	686,004
Common stock issuable on contingent basis							107,617		202,650
Common stock issuable on non-contingent basis								170,988
Common stock issued on non-contingent basis						170,988
Maximum earn-out consideration payable over all years		$7,000	$7,000

Stockholders_Equity_Lazard_Gro

Stockholders' Equity - Lazard Group Distributed Amounts to LAZ-MD Holdings and Subsidiaries of Lazard Ltd (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Schedule Of Group Distributions [Line Items]
Total distributed by Lazard Group	$60,931	$66,219
LAZ-MD Holdings [Member]
Schedule Of Group Distributions [Line Items]
Total distributed by Lazard Group	565	3,729
Subsidiaries of Lazard Ltd [Member]
Schedule Of Group Distributions [Line Items]
Total distributed by Lazard Group	60,931	66,219
Lazard Ltd [Member]
Schedule Of Group Distributions [Line Items]
Total distributed by Lazard Group	$61,496	$69,948

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

1 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

In Thousands, except Share data, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Oct. 23, 2013

Sep. 30, 2013

Dec. 31, 2012

Oct. 31, 2012

Apr. 30, 2012

Oct. 31, 2011

Feb. 28, 2011

Sep. 30, 2013

Oct. 31, 2013

Lazard Ltd [Member]

Lazard Ltd [Member]

Class A Common Stock [Member]

Class A Common Stock [Member]

Series A Preferred Stock [Member]

Series A Preferred Stock [Member]

Share Repurchase Program [Member]

Share Repurchase Program [Member]

Share Repurchase Program [Member]

Share Repurchase Program [Member]

Share Repurchase Program [Member]

Share Repurchase Program [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Schedule Of Stockholders Equity [Line Items]

Shares in exchange of a like number of common membership interests

839,658

191,701

Stock/membership interest repurchase program authorized amount

$200,000

$125,000

$125,000

$250,000

$100,000

Share repurchase program expiration date

31-Dec-14

31-Dec-13

31-Dec-13

31-Dec-12

31-Dec-14

31-Dec-15

Number of shares/common membership interests purchased during current year

2,201,657

Aggregate cost of shares/common membership interests purchased

77,934

Share repurchase amount unused

$76,132

Authorized shares of preferred stock

15,000,000

15,000,000

15,000,000

Par value of preferred stock

$0.01

$0.01

$0.01

Outstanding shares of preferred stock

7,921

7,921

DIVIDENDS DECLARED PER SHARE OF COMMON STOCK

$0.25

$0.20

$0.50

$0.56

$0.25

Dividend payable date

22-Nov-13

Dividend date of record

4-Nov-13

Dividend declare date

23-Oct-13

Stockholders_Equity_Accumulate

Stockholders' Equity - Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	($110,541)
Other comprehensive gain (loss) before reclassifications	-21,730
Adjustments for items reclassified to earnings, net of tax	4,419
Net other comprehensive income (loss)	-17,311
Ending balance	-127,852
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	19,405
Other comprehensive gain (loss) before reclassifications	-18,610
Adjustments for items reclassified to earnings, net of tax
Net other comprehensive income (loss)	-18,610
Ending balance	795
Interest Rate Hedge [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-2,502
Other comprehensive gain (loss) before reclassifications
Adjustments for items reclassified to earnings, net of tax	791
Net other comprehensive income (loss)	791
Ending balance	-1,711
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-128,536
Other comprehensive gain (loss) before reclassifications	-2,669
Adjustments for items reclassified to earnings, net of tax	3,653
Net other comprehensive income (loss)	984
Ending balance	-127,552
Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-111,633
Other comprehensive gain (loss) before reclassifications	-21,279
Adjustments for items reclassified to earnings, net of tax	4,444
Net other comprehensive income (loss)	-16,835
Ending balance	-128,468
Noncontrolling Interests [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	-1,092
Other comprehensive gain (loss) before reclassifications	451
Adjustments for items reclassified to earnings, net of tax	25
Net other comprehensive income (loss)	476
Ending balance	($616)

Stockholders_Equity_Gains_Loss

Stockholders' Equity - Gains (Losses) Reclassified Out of AOCI (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less - related income taxes	$18,370	$13,053	$31,335	$32,191
Net of tax			4,419
Interest Rate Hedge [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax			791
Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax			3,653
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	1,487		4,444
Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Hedge [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of interest rate hedge	264		791
Reclassification out of Accumulated Other Comprehensive Income [Member] | Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization relating to employee benefit plans	1,627		4,859
Less - related income taxes	404		1,206
Net of tax	$1,223		$3,653

Stockholders_Equity_Changes_in

Stockholders' Equity - Changes in Ownership Interests (Detail)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Lazard Ltd [Member]
Change In Ownership Interest [Line Items]
Beginning balance (in shares)	128,216,423	123,009,311
Common membership interest activity in connection with Exchanges for Class A common stock	839,658	191,701
Ending balance (in shares)	129,056,081	123,201,012
Percentage of Ownership, Beginning Balance	98.80%	94.80%
Percentage of Ownership, Ending Balance	99.50%	94.90%
LAZ-MD Holdings [Member]
Change In Ownership Interest [Line Items]
Beginning balance (in shares)	1,549,667	6,756,779
Common membership interest activity in connection with Exchanges for Class A common stock	-839,658	-191,701
Ending balance (in shares)	710,009	6,565,078
Percentage of Ownership, Beginning Balance	1.20%	5.20%
Percentage of Ownership, Ending Balance	0.50%	5.10%
Total Lazard Group Common Membership Interests [Member]
Change In Ownership Interest [Line Items]
Beginning balance (in shares)	129,766,090	129,766,090
Common membership interest activity in connection with Exchanges for Class A common stock
Ending balance (in shares)	129,766,090	129,766,090

Stockholders_Equity_Net_Income

Stockholders' Equity - Net Income Attributable to Noncontrolling Interests (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	$2,466	$372	$5,323	$7,217
Noncontrolling interests	74,287		74,287		81,884
Edgewater [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	2,018	-1,704	4,671	2,168
Noncontrolling interests	71,075		71,075		75,262
LAZ-MD Holdings [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	365	1,937	862	4,956
Noncontrolling interests	2,629		2,629		5,405
Other [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	83	139	-210	93
Noncontrolling interests	$583		$583		$1,217

Incentive_Plans_Additional_Inf

Incentive Plans - Additional Information (Detail) (USD $)

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

In Thousands, except Share data, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Mar. 31, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Non-Executive [Member]

Lazard Fund Interests [Member]

DSUs [Member]

DSUs [Member]

RSUs [Member]

RSUs [Member]

RSUs [Member]

RSUs [Member]

RSUs [Member]

Restricted Stock [Member]

Restricted Stock [Member]

PRSUs [Member]

PRSUs [Member]

PRSUs [Member]

PRSUs [Member]

Class A Common Stock [Member]

Class A Common Stock [Member]

Class A Common Stock [Member]

Class A Common Stock [Member]

Class A Common Stock [Member]

Class A Common Stock [Member]

Liability Awards [Member]

Liability Awards [Member]

Liability Awards [Member]

Executive Officers [Member]

March 2015 [Member]

March 2016 [Member]

2005 Plan [Member]

Awarded under 2008 Plan [Member]

RSUs [Member]

RSUs [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shares authorized pertaining to share based compensation arrangements, 2005 Plan

25,000,000

Percentage of outstanding Class A common stock

30.00%

Percentage of annual compensation received by directors in the form of DSUs

55.00%

Annual compensation paid in DSUs

39,315

49,982

Units granted under the directors deferred unit plan

5,880

7,988

Withholding taxes in lieu of share delivery

18,631

28,129

3,471,813

1,331,812

Delivery of common stock associated with stock awards

5,891,979

3,093,722

1,709,878

158,051

Forfeitures of shares

42,432

RSUs modified through a forward purchase agreement

958,213

Liability awards, compensation expense

$1,690

Liability awards

28,612

Unrecognized compensation expense

$196,000

$9,000

$23,000

Unrecognized compensation expense, years

1 year 8 months 12 days

1 year 2 months 12 days

1 year 6 months

1 year 8 months 12 days

Shares granted

45,195

57,970

4,862,379

8,121,632

448,128

Vesting period associated with PRSUs

33.00%

67.00%

Percentage of target number of shares subject to each PRSU no longer subject to forfeiture due to threshold level of performance being achieved

25.00%

Weighted Average Grant Date Fair Value, Granted

$34.18

$23.57

$36.92

$27.56

$36.11

Incentive_Plans_Summary_of_Imp

Incentive Plans - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based incentive awards:
Share-based incentive awards	$55,260	$67,689	$183,341	$220,175
RSUs [Member]
Share-based incentive awards:
Share-based incentive awards	46,095	65,952	163,184	211,271
PRSUs [Member]
Share-based incentive awards:
Share-based incentive awards	6,467		8,900
Restricted Stock [Member]
Share-based incentive awards:
Share-based incentive awards	2,627	1,659	9,712	7,538
DSUs [Member]
Share-based incentive awards:
Share-based incentive awards	$71	$78	$1,545	$1,366

Incentive_Plans_Summary_of_Imp1

Incentive Plans - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense (Parenthetical) (Detail) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Staff reductions and Cost Saving Initiatives	$0	$247
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Staff reductions and Cost Saving Initiatives	$0	$9,099

Incentive_Plans_Schedule_of_Is

Incentive Plans - Schedule of Issuance of RSUs and Charges to Retained Earnings (Detail) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of RSUs issued	250,834	479,958
Charges to retained earnings, net of estimated forfeitures	$8,216	$11,770

Incentive_Plans_Schedule_of_Ac

Incentive Plans - Schedule of Activity Relating to RSUs and DSUs (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units, Beginning Balance	21,481,131	20,751,829
Units, Granted	4,862,379	8,121,632
Units, Forfeited	-239,117	-401,065
Units, Vested	-9,363,792	-4,425,534
Units, Ending Balance	16,740,601	24,046,862
Weighted Average Grant Date Fair Value, Beginning Balance	$33.92	$36.84
Weighted Average Grant Date Fair Value, Granted	$36.92	$27.56
Weighted Average Grant Date Fair Value, Forfeited	$34.63	$35.49
Weighted Average Grant Date Fair Value, Vested	$34.78	$34.43
Weighted Average Grant Date Fair Value, Ending Balance	$34.30	$34.16
DSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units, Beginning Balance	204,496	140,660
Units, Granted	45,195	57,970
Units, Forfeited
Units, Vested
Units, Ending Balance	249,691	198,630
Weighted Average Grant Date Fair Value, Beginning Balance	$31.47	$34.83
Weighted Average Grant Date Fair Value, Granted	$34.18	$23.57
Weighted Average Grant Date Fair Value, Forfeited
Weighted Average Grant Date Fair Value, Vested
Weighted Average Grant Date Fair Value, Ending Balance	$31.96	$31.54

Incentive_Plans_Schedule_of_Ac1

Incentive Plans - Schedule of Activity Relating to RSUs and DSUs (Parenthetical) (Detail) (RSUs [Member])	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend participation rights	250,834	479,958

Incentive_Plans_Summary_of_Act

Incentive Plans - Summary of Activity Related to Shares of Restricted Class A Common Stock (Detail) (RSA [Member], USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
RSA [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units, Beginning Balance	1,972,609	95,332
Units, Granted/Exchanged	368,736	577,323
Units, Forfeited	-35,794	-21,178
Units, Vested	-1,728,509	-186,180
Units, Ending Balance	577,042	465,297
Weighted Average Grant Date Fair Value, Beginning Balance	$34.85	$37.63
Weighted Average Grant Date Fair Value, Granted/Exchanged	$36.74	$29.25
Weighted Average Grant Date Fair Value, Forfeited	$33.35	$29.51
Weighted Average Grant Date Fair Value, Vested	$36	$31.60
Weighted Average Grant Date Fair Value, Ending Balance	$32.72	$30.02

Incentive_Plans_Summary_of_Fun

Incentive Plans - Summary of Fund Interests and Other Similar Deferred Compensation Arrangements (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Prepaid Compensation Asset, Beginning Balance	$47,445	$17,782
Prepaid Compensation Asset, Granted	72,217	64,658
Prepaid Compensation Asset, Settled
Prepaid Compensation Asset, Forfeited	-765	-1,607
Prepaid Compensation Asset, Amortization	-44,195	-24,508
Prepaid Compensation Asset, Increase in fair value of underlying investments
Prepaid Compensation Asset, Adjustment for estimated forfeitures
Prepaid Compensation Asset, Other	-217	101
Prepaid Compensation Asset, Ending Balance	74,485	56,426
Compensation Liability, Beginning Balance	97,593	29,900
Compensation Liability, Granted	72,217	64,658
Compensation Liability, Settled	-22,903	-8,640
Compensation Liability, Forfeited	-985	-1,706
Compensation Liability, Amortization
Compensation Liability, Increase in fair value of underlying investments	7,767	4,639
Compensation Liability, Adjustment for estimated forfeitures	3,175	2,202
Compensation Liability, Other	-558
Compensation Liability, Ending Balance	$156,306	$91,053

Incentive_Plans_Summary_of_Imp2

Incentive Plans - Summary of Impact of Fund Interests and Other Similar Deferred Compensation Arrangements (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Compensation expense:
Amortization, net of forfeitures	$15,049	$9,626	$47,150	$26,611
Change in fair value of underlying investments	7,519	4,728	7,767	4,639
Total	$22,568	$14,354	$54,917	$31,250

Incentive_Plans_Summary_of_Imp3

Incentive Plans - Summary of Impact of Fund Interests and Other Similar Deferred Compensation Arrangements (Parenthetical) (Detail) (Lazard Fund Interests and other similar deferred compensation arrangements [Member], USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
Lazard Fund Interests and other similar deferred compensation arrangements [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Staff reductions and Cost Saving Initiatives	$0	$2,665

Employee_Benefit_Plans_Additio

Employee Benefit Plans - Additional Information (Detail)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2011	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
	USD ($)	USD ($)	Other Non-U.S. Pension Plans [Member]	U.K. pension plans [Member]	U.K. pension plans [Member]	U.K. pension plans [Member]	U.K. pension plans [Member]	U.S. Pension Plans [Member]	Payments from 2014 through 2020 [Member]	Payments from 2012 through 2020 [Member]
			USD ($)	USD ($)	GBP (£)	USD ($)	GBP (£)	USD ($)	GBP (£)	GBP (£)
Defined Benefit Plan Disclosure [Line Items]
Company contribution to pension plans			$0	$1,545,000	£ 1,000,000	$3,687,000	£ 2,300,000	$0
Additional contribution to plan assets or escrow account									1,000,000	1,000,000
Amended amount from previous escrow arrangement							10,200,000
Aggregate amount in account security arrangement	$16,500,000	$16,500,000

Employee_Benefit_Plans_Compone

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Plans [Member]
Components of Net Benefit Cost (Credit):
Service cost	$315	$166	$938	$504
Interest cost	6,744	6,862	20,193	20,649
Expected return on plan assets	-6,701	-6,637	-20,090	-19,931
Amortization of:
Prior service cost	708	668	2,114	2,056
Net actuarial loss	919	412	2,745	1,243
Settlement loss				886
Net benefit cost	1,985	1,471	5,900	5,407
Medical Plan [Member]
Components of Net Benefit Cost (Credit):
Service cost	12	15	39	45
Interest cost	46	53	137	158
Expected return on plan assets
Amortization of:
Prior service cost
Net actuarial loss
Settlement loss
Net benefit cost	$58	$68	$176	$203

Employee_Benefit_Plans_Compone1

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Parenthetical) (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Compensation And Retirement Disclosure [Abstract]
Recognition of actuarial losses	$1,935
Settlements loss	886
Settlement charges	$1,049

Cost_Saving_Initiatives_Schedu

Cost Saving Initiatives - Schedule of Expenses and Cumulative Expenses Associated With Implementation of Cost Savings Initiatives (Detail) (USD $)

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Compensation and Benefits [Member]

Other [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Compensation and Benefits [Member]

Other [Member]

Financial Advisory [Member]

Financial Advisory [Member]

Financial Advisory [Member]

Asset Management [Member]

Asset Management [Member]

Asset Management [Member]

Corporate [Member]

Corporate [Member]

Corporate [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Cumulative [Member]

Compensation and Benefits [Member]

Other [Member]

Compensation and Benefits [Member]

Other [Member]

Compensation and Benefits [Member]

Other [Member]

Financial Advisory [Member]

Financial Advisory [Member]

Financial Advisory [Member]

Asset Management [Member]

Asset Management [Member]

Asset Management [Member]

Corporate [Member]

Corporate [Member]

Corporate [Member]

Compensation and Benefits [Member]

Other [Member]

Compensation and Benefits [Member]

Other [Member]

Compensation and Benefits [Member]

Other [Member]

Restructuring and Related Cost [Abstract]

Cost Saving Initiatives

$64,703

$51,399

$13,304

$167,279

$151,386

$15,893

$47,779

$45,746

$2,033

$235

$236

($1)

$16,689

$5,417

$11,272

$125,311

$121,879

$3,432

$13,024

$12,292

$732

$28,944

$17,215

$11,729

Cost_Saving_Initiatives_Activi

Cost Saving Initiatives - Activity Related to Obligations Pursuant to Cost Saving Initiatives (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$47,842
New charges	64,703
Non-cash charges	-15,394
Settlements	-71,112
Ending Balance	26,039
Accrued Compensation and Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	46,128
New charges	51,399
Non-cash charges	-12,007
Settlements	-68,813
Ending Balance	16,707
Other Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,714
New charges	13,304
Non-cash charges	-3,387
Settlements	-2,299
Ending Balance	$9,332

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Taxes [Line Items]
Provisions for income tax	$18,370	$13,053	$31,335	$32,191
Effective income tax rates	22.60%	27.90%	21.80%	24.90%
U.S. federal statutory income tax rate			35.00%
LFCM Holdings [Member]
Income Taxes [Line Items]
Percentage of cash savings required to pay under the tax receivable agreement			85.00%

Net_Income_Per_Share_of_Class_2

Net Income Per Share of Class A Common Stock - Company's Basic and Diluted Net Income Per Share and Weighted Average Shares Outstanding (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net income attributable to Lazard Ltd	$60,282	$33,301	$106,995	$89,674
Add - adjustment associated with Class A common stock issuable on a non-contingent basis		3		6
Net income attributable to Lazard Ltd - basic	60,282	33,304	106,995	89,680
Adjustments to income relating to interest expense and changes in net income attributable to noncontrolling interests resulting from assumed Class A common stock issuances in connection with share-based incentive compensation and exchangeable interests, net of tax	316	1,804	787	4,680
Net income attributable to Lazard Ltd - diluted	$60,598	$35,108	$107,782	$94,360
Weighted average number of shares of Class A common stock outstanding	121,441,956	114,689,712	119,797,545	116,949,317
Add - adjustment for shares of Class A common stock issuable on a non-contingent basis	757,998	913,639	758,502	740,087
Weighted average number of shares of Class A common stock outstanding - basic	122,199,954	115,603,351	120,556,047	117,689,404
Weighted average number of incremental shares of Class A common stock issuable from share-based incentive compensation and exchangeable interests	12,042,190	19,776,685	12,617,953	17,847,646
Weighted average number of shares of Class A common stock outstanding - diluted	134,242,144	135,380,036	133,174,000	135,537,050
Net income attributable to Lazard Ltd per share of Class A common stock:
Basic	$0.49	$0.29	$0.89	$0.76
Diluted	$0.45	$0.26	$0.81	$0.70

Related_Parties_Amounts_Receiv

Related Parties - Amounts Receivable from and Payable to Related Parties (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Related Party Transaction [Line Items]
Amounts receivables from related parties	$14,276	$23,801
Amounts payables to related parties	4,695	3,648
LFCM Holdings [Member]
Related Party Transaction [Line Items]
Amounts receivables from related parties	13,015	20,529
Amounts payables to related parties	4,335	2,943
Other [Member]
Related Party Transaction [Line Items]
Amounts receivables from related parties	1,261	3,272
Amounts payables to related parties	$360	$705

Related_Parties_Additional_Inf

Related Parties - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

LFCM Holdings [Member]

MBA Lazard Holdings S.A. [Member]

MBA Lazard Holdings S.A. [Member]

LAZ-MD Holdings [Member]

LAZ-MD Holdings [Member]

LAZ-MD Holdings [Member]

LAZ-MD Holdings [Member]

Administrative and Support Services and Others [Member]

Administrative and Support Services and Others [Member]

Referral Fees for Underwriting and Private Placement Transactions [Member]

Referral Fees for Underwriting and Private Placement Transactions [Member]

Referral Fees [Member]

Referral Fees [Member]

Administrative Services Agreement [Member]

Administrative Services Agreement [Member]

Administrative Services Agreement [Member]

Administrative Services Agreement [Member]

Related Party Transaction [Line Items]

Amounts recorded relating to the administrative services agreement

$534

$666

$1,466

$2,181

$250

$188

$750

$563

Amounts recorded relating to net referral fees for underwriting, private placement, and restructuring transactions

1,633

182

1,163

4,548

Receivables from related party

5,038

14,299

7,977

6,230

Payables to related party

$4,335

$2,943

Percentage of ownership

50.00%

50.00%

Regulatory_Authorities_Additio

Regulatory Authorities - Additional Information (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
LFNY [Member]
Regulatory Authorities [Line Items]
Specified fixed percentage, minimum required capital	6.67%
Minimum net capital requirement as defined under securities exchange act	$100
Regulatory net capital	84,678
Regulatory capital in excess of minimum requirement	81,181
U.K. Subsidiaries [Member]
Regulatory Authorities [Line Items]
Regulatory net capital	66,007
Regulatory capital in excess of minimum requirement	51,404
CFLF [Member]
Regulatory Authorities [Line Items]
Regulatory net capital	192,042
Regulatory capital in excess of minimum requirement	158,224
Other U.S. and Non-U.S. Subsidiaries [Member]
Regulatory Authorities [Line Items]
Regulatory net capital	113,317
Regulatory capital in excess of minimum requirement	$75,584

Segment_Information_Segments_C

Segment Information - Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net Revenue (Expense)	$480,354	$428,806	$1,372,662	$1,351,755
Operating Expenses	399,236	382,080	1,229,009	1,222,673
Operating Income (Loss)	81,118	46,726	143,653	129,082
Total Assets
Total Assets	2,956,456		2,956,456		2,986,893
Financial Advisory [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenue (Expense)	233,842	219,973	665,611	739,793
Operating Expenses	218,015	212,449	674,689	693,546
Operating Income (Loss)	15,827	7,524	-9,078	46,247
Total Assets
Total Assets	697,183		697,183		793,007
Asset Management [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenue (Expense)	252,094	221,516	741,618	647,096
Operating Expenses	168,895	160,869	511,526	477,989
Operating Income (Loss)	83,199	60,647	230,092	169,107
Total Assets
Total Assets	632,526		632,526		566,677
Corporate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenue (Expense)	-5,582	-12,683	-34,567	-35,134
Operating Expenses	12,326	8,762	42,794	51,138
Operating Income (Loss)	-17,908	-21,445	-77,361	-86,272
Total Assets
Total Assets	$1,626,747		$1,626,747		$1,627,209