Lazard 10-Q 31 Jul 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 20, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	LZD
Entity Registrant Name	LAZARD GROUP LLC
Entity Central Index Key	1,326,141
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	0
Subsidiaries of Lazard Ltd [Member]
Document Information [Line Items]
Membership Interests, Shares Outstanding		2

Condensed Consolidated Statemen

Condensed Consolidated Statements of Financial Condition - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents		$ 779,539	$ 1,470,296
Deposits with banks and short-term investments		1,000,662	935,431
Cash deposited with clearing organizations and other segregated cash		37,089	35,539
Receivables (net of allowance for doubtful accounts of $34,906 and $23,692 at June 30, 2018 and December 31, 2017, respectively):
Fees		610,488	487,800
Customers and other		103,909	83,816
Lazard Ltd subsidiaries		106,124	17,135
Total receivables, net		820,521	588,751
Investments		505,194	427,186
Property (net of accumulated amortization and depreciation of $324,863 and $317,816 at June 30, 2018 and December 31, 2017, respectively)		214,735	203,828
Goodwill and other intangible assets (net of accumulated amortization of $62,472 and $61,202 at June 30, 2018 and December 31, 2017, respectively)		360,687	368,034
Deferred tax assets		46,997	46,646
Other assets		305,195	224,862
Total Assets		4,070,619	4,300,573
Liabilities:
Deposits and other customer payables		1,055,245	992,338
Accrued compensation and benefits		402,267	591,394
Senior debt		1,191,277	1,190,383
Payable to Lazard Ltd subsidiaries		68,739	65,271
Deferred tax liabilities		7,093	9,195
Other liabilities		564,571	545,092
Total Liabilities		3,289,192	3,393,673
Commitments and contingencies
MEMBERS’ EQUITY
Members' equity (net of 8,882,090 and 9,907,479 shares of Lazard Ltd Class A common stock, at a cost of $410,079 and $411,560 at June 30, 2018 and December 31, 2017, respectively)		935,787	1,043,574
Accumulated other comprehensive loss, net of tax		(211,757)	(195,256)
Total Lazard Group LLC Members' Equity		724,030	848,318
Noncontrolling interests		57,397	58,582
Total Members’ Equity	[1]	781,427	906,900
Total Liabilities and Members’ Equity		$ 4,070,619	$ 4,300,573
[1]	As of January 1, 2018 and June 30, 2018, in addition to profit participation interests, there were two managing member interests.

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts receivables	$ 34,906	$ 23,692
Property, accumulated amortization and depreciation	324,863	317,816
Other intangible assets, accumulated amortization	$ 62,472	$ 61,202
Lazard Ltd common stock, shares	8,882,090	9,907,479
Lazard Ltd common stock, cost	$ 410,079	$ 411,560

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
REVENUE
Interest income	$ 2,255	$ 1,605	$ 4,943	$ 3,344
Total revenue	769,157	729,724	1,536,890	1,367,025
Interest expense	14,518	13,698	28,990	28,522
Net revenue	754,639	716,026	1,507,900	1,338,503
OPERATING EXPENSES
Amortization and other acquisition-related (benefits) costs	(538)	463	84	1,611
Other	10,290	12,278	36,424	21,357
Total operating expenses	562,825	540,780	1,129,134	1,010,245
OPERATING INCOME	191,814	175,246	378,766	328,258
Provision for income taxes	31,445	32,440	50,060	54,435
NET INCOME	160,369	142,806	328,706	273,823
LESS - NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	1,416	522	3,385	3,399
NET INCOME ATTRIBUTABLE TO LAZARD GROUP LLC	158,953	142,284	325,321	270,424
Other [Member]
REVENUE
Revenue	12,188	24,215	31,065	51,937
Investment Banking and Other Advisory Fees [Member]
REVENUE
Revenue	418,823	410,025	826,895	744,941
Asset Management Fees [Member]
REVENUE
Revenue	335,891	293,879	673,987	566,803
Compensation and Benefits [Member]
OPERATING EXPENSES
Operating expenses	414,615	413,532	817,922	774,848
Occupancy and Equipment [Member]
OPERATING EXPENSES
Operating expenses	29,041	30,793	59,113	58,252
Marketing and Business Development [Member]
OPERATING EXPENSES
Operating expenses	28,164	23,931	53,772	43,418
Technology and Information Services [Member]
OPERATING EXPENSES
Operating expenses	32,501	31,979	65,730	55,958
Professional Services [Member]
OPERATING EXPENSES
Operating expenses	15,525	9,468	27,678	20,554
Fund Administration and Outsourced Services [Member]
OPERATING EXPENSES
Operating expenses	$ 33,227	$ 18,336	$ 68,411	$ 34,247

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
NET INCOME	$ 160,369	$ 142,806	$ 328,706	$ 273,823
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX:
Currency translation adjustments	(40,576)	25,323	(21,627)	38,622
Employee benefit plans:
Actuarial gain (loss) (net of tax expense (benefit) of $1,746 and $(2,215) for the three months ended June 30, 2018 and 2017, respectively, and $404 and $(2,476) for the six months ended June 30, 2018 and 2017, respectively)	8,300	(8,609)	3,286	(9,104)
Adjustment for items reclassified to earnings (net of tax expense of $468 and $196 for the three months ended June 30, 2018 and 2017, respectively, and $684 and $472 for the six months ended June 30, 2018 and 2017, respectively)	777	1,356	1,839	2,442
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(31,499)	18,070	(16,502)	31,960
COMPREHENSIVE INCOME	128,870	160,876	312,204	305,783
LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	1,415	523	3,384	3,400
COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD GROUP LLC	$ 127,455	$ 160,353	$ 308,820	$ 302,383

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Tax expense (benefit) on actuarial gain (loss), employee benefit plans	$ 1,746	$ (2,215)	$ 404	$ (2,476)
Tax expense, adjustment for items reclassified to earnings, employee benefit plans	$ 468	$ 196	$ 684	$ 472

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
NET INCOME	$ 328,706	$ 273,823
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of property	16,536	15,367
Amortization of deferred expenses and share-based incentive compensation	224,485	208,245
Amortization and other acquisition-related costs	84	1,611
Deferred tax provision (benefit)	(3,725)	3,202
(Increase) decrease in operating assets:
Receivables-net	(243,419)	13,987
Investments	(79,998)	30,454
Other assets	(131,417)	(87,708)
Increase (decrease) in operating liabilities:
Accrued compensation and benefits and other liabilities	(120,330)	(68,001)
Net cash (used in) provided by operating activities	(9,078)	390,980
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property	(31,846)	(9,408)
Disposals of property	1,328	195
Net cash used in investing activities	(30,518)	(9,213)
Proceeds from:
Customer deposits	70,194	196,947
Contributions from noncontrolling interests	491
Other financing activities	25
Payments for:
Capital lease obligations	(17)	(7,320)
Distributions to noncontrolling interests	(5,060)	(1,733)
Purchase of Lazard Ltd Class A common stock	(223,795)	(184,892)
Distributions to members	(265,592)	(244,722)
Settlement of vested share-based incentive compensation	(109,218)	(66,086)
Other financing activities	(4,681)	(8,980)
Net cash used in financing activities	(537,653)	(316,786)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	(46,727)	91,054
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	(623,976)	156,035
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH—January 1	2,441,266	1,580,138
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH—June 30	$ 1,817,290	$ 1,736,173

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH WITHIN THE CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION:
Cash and cash equivalents	$ 779,539	$ 1,470,296
Deposits with banks and short-term investments	1,000,662	935,431
Cash deposited with clearing organizations and other segregated cash	37,089	35,539
TOTAL CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	$ 1,817,290	$ 2,441,266	$ 1,736,173	$ 1,580,138

Condensed Consolidated Stateme9

Condensed Consolidated Statements of Changes in Members' Equity - USD ($) $ in Thousands		Total	Members' Equity [Member]	Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]	Total Lazard Group LLC Members' Equity [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2016	[1]	$ 736,140	$ 949,669	$ (270,775)	$ 678,894	$ 57,246
Adjustment for the cumulative effect on prior years from the adoption of new accounting guidance related to share-based incentive compensation at Dec. 31, 2016		4,945	4,945		4,945
Balance, as adjusted at Dec. 31, 2016		741,085	954,614	(270,775)	683,839	57,246
Comprehensive income (loss):
Net income		273,823	270,424		270,424	3,399
Other comprehensive income (loss) - net of tax		31,960		31,959	31,959	1
Amortization of share-based incentive compensation		163,001	163,001		163,001
Distributions to members and noncontrolling interests, net		(246,455)	(244,722)		(244,722)	(1,733)
Purchase of Lazard Ltd Class A common stock		(184,892)	(184,892)		(184,892)
Delivery of Lazard Ltd Class A common stock in connection with share-based incentive compensation		(66,086)	(66,086)		(66,086)
Business acquisitions and related equity transactions:
Lazard Ltd Class A common stock issuable (including related amortization)		185	185		185
Other		(3,679)	(3,883)		(3,883)	204
Balance at Jun. 30, 2017	[1]	708,942	888,641	(238,816)	649,825	59,117
Balance at Mar. 31, 2017				(256,885)
Comprehensive income (loss):
Net income		142,806
Other comprehensive income (loss) - net of tax		18,070		18,069
Balance at Jun. 30, 2017	[1]	708,942	888,641	(238,816)	649,825	59,117
Balance at Dec. 31, 2017	[2]	906,900	1,043,574	(195,256)	848,318	58,582
Comprehensive income (loss):
Net income		328,706	325,321		325,321	3,385
Other comprehensive income (loss) - net of tax		(16,502)		(16,501)	(16,501)	(1)
Amortization of share-based incentive compensation		169,830	169,830		169,830
Distributions to members and noncontrolling interests, net		(270,161)	(265,592)		(265,592)	(4,569)
Purchase of Lazard Ltd Class A common stock		(223,795)	(223,795)		(223,795)
Delivery of Lazard Ltd Class A common stock in connection with share-based incentive compensation		(109,218)	(109,218)		(109,218)
Business acquisitions and related equity transactions:
Lazard Ltd Class A common stock issuable (including related amortization)		185	185		185
Other		(4,518)	(4,518)		(4,518)
Balance at Jun. 30, 2018	[2]	781,427	935,787	(211,757)	724,030	57,397
Balance at Mar. 31, 2018				(180,259)
Comprehensive income (loss):
Net income		160,369
Other comprehensive income (loss) - net of tax		(31,499)		(31,498)
Balance at Jun. 30, 2018	[2]	$ 781,427	$ 935,787	$ (211,757)	$ 724,030	$ 57,397
[1]	As of January 1, 2017 and June 30, 2017, in addition to profit participation interests, there were two managing member interests.
[2]	As of January 1, 2018 and June 30, 2018, in addition to profit participation interests, there were two managing member interests.

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation	1. ORGANIZATION AND BASIS OF PRESENTATION Organization The accompanying condensed consolidated financial statements are those of Lazard Group LLC and its subsidiaries (collectively referred to as “Lazard Group” or the “Company”). Lazard Group is a Delaware limited liability company and is governed by an Amended and Restated Operating Agreement dated as of October 26, 2015, as amended (the “Operating Agreement”). Lazard Ltd, a Bermuda holding company, and its subsidiaries (collectively referred to as “Lazard Ltd”), including its indirect investment in 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 100% of all outstanding Lazard Group common membership interests as of June 30, 2018 and December 31, 2017. Lazard Ltd, through its control of the managing members of Lazard Group, controls Lazard Group. Lazard Group’s 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”), capital advisory, capital raising, restructurings, shareholder advisory, sovereign advisory and other strategic advisory, and • Asset Management, which offers a broad range of global investment solutions and investment management services in equity and fixed income strategies, asset allocation 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, deferred tax assets, outstanding indebtedness, certain contingent obligations, and assets and liabilities associated with Lazard Group’s Paris-based subsidiary Lazard Frères Banque SA (“LFB”). Basis of Presentation The accompanying condensed consolidated financial statements of Lazard Group 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 Group’s Annual Report on Form 10-K for the year ended December 31, 2017. The accompanying December 31, 2017 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. For example, 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 six month periods ended June 30, 2018 are not indicative of the results to be expected for any future interim or annual period. The condensed consolidated financial statements include 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 Lazard Frères Gestion SAS (“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 entities in which it has a controlling financial interest. The Company consolidates: • Voting interest entities (“VOEs”) where the Company holds a majority of the voting interest in such VOEs, and • Variable interest entities (“VIEs”) where the Company is the primary beneficiary having the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses of, or receive benefits from, the VIE that could be potentially significant to the VIE. 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 either (i) applies the equity method of accounting in which it records a proportionate share of the entity’s net earnings, or (ii) elects the option to measure at fair value. Intercompany transactions and balances have been eliminated. Certain prior period amounts have been reclassified to conform to the current period presentation, specifically related to the adoption of new guidance impacting the condensed consolidated statements of cash flows (see Note 2).

Recent Accounting Developments

Recent Accounting Developments	6 Months Ended
	Jun. 30, 2018
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Recent Accounting Developments	2. RECENT ACCOUNTING DEVELOPMENTS Revenue from Contracts with Customers— In May 2014, the FASB issued comprehensive new revenue recognition guidance. The guidance requires a company to recognize revenue when it transfers promised services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those services and requires enhanced disclosures. The guidance also changes the accounting for certain contract costs, including whether they may be offset against revenue in the condensed consolidated statements of operations. On July 9, 2015, the FASB approved the deferral of the effective date of the new revenue guidance by one year to annual reporting periods beginning after December 15, 2017. The guidance may be adopted using a full retrospective approach or a modified cumulative effect approach. The Company adopted the revenue recognition guidance upon its effective date of January 1, 2018 using the modified cumulative effect approach. The Company applied the new guidance to contracts that have not yet been completed as of the adoption date. The Company’s adoption efforts included the identification of revenue within the scope of the guidance and the evaluation of revenue contracts. The Company evaluated the potential impact of the new guidance, including (i) the timing of revenue recognition for Financial Advisory and Asset Management fees and (ii) the presentation of certain contract costs. With respect to revenue recognition, the Company assessed the impact of the new guidance on the recognition of fees for Financial Advisory (e.g., transaction completion, transaction announcement and retainers), and Asset Management (e.g., management and incentive fees). This assessment included an analysis of whether the Company’s fulfillment of its performance obligations would be deemed to occur over time, or at specific points in time, under the new guidance. Specifically, recognition would be deemed to occur over time if the client receives and consumes benefits from the services as the Company performs the services. The Company concluded that Financial Advisory and Asset Management fees would typically be recognized over time as performance occurs, subject to constraints, using an appropriate measure of progress based on resources consumed, which is consistent with when the client receives benefits. There was no material impact to the Company’s recognition of revenue upon adoption of the new guidance. The new guidance requires the Company to prospectively present certain contract costs on a gross basis. The most significant changes with respect to presentation relate to (a) certain distribution costs within our Asset Management business and (b) certain reimbursable deal costs within our Financial Advisory business, both of which were previously presented net against revenues and are now presented as expenses on a gross basis under the new guidance because the Company is primarily responsible for fulfilling the promise of the arrangement. For the three month and six month periods ended June 30, 2018, the presentation of such costs on a gross basis resulted in an increase to net revenue of $24,053 and $47,609, respectively, primarily comprised of increases to asset management fees and investment banking and other advisory fees. In addition, there was a corresponding increase to operating expenses of $24,053 and $47,609, respectively, primarily comprised of an increase to distribution costs presented within fund administration and outsourced services and an increase to reimbursable deal costs presented within marketing and business development. These amounts would have been presented on a net basis prior to the adoption of the new guidance, and there was no material impact to net income as a result of the gross basis of presentation under the new guidance. See Note 3 for further information on contracts within the scope of the new guidance. Classification of Certain Cash Receipts and Cash Payments— In August and November 2016, the FASB issued updated guidance which clarifies how a company should classify certain cash receipts and cash payments on the statement of cash flows and clarifies that restricted cash should be included in the total of cash and cash equivalents on the statement of cash flows. The new guidance for both updates is effective for annual and interim periods beginning after December 15, 2017 and is to be applied on a retrospective basis. The Company adopted this new guidance on January 1, 2018. The adoption of the new guidance in the first quarter of 2018 resulted in the reclassification of “cash deposited with clearing organization and other segregated cash” and “deposits with banks and short-term investments” from operating activities to components of “cash and cash equivalents and restricted cash” on the condensed consolidated statement of cash flows. In addition, the Company reclassified cash flows related to customer deposits from operating activities to financing activities. This resulted in changes in deposits with banks and short-term investments and customer deposits no longer being reflected in cash flows from operating activities. Except for the reclassification of these items on the condensed consolidated statement of cash flows, the new guidance had no impact on the Company’s financial statements. Clarifying the Definition of a Business— In January 2017, the FASB issued updated guidance to clarify the definition of a business within the context of business combinations. The updated guidance requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, such asset or group of assets is not a business. This updated guidance is expected to reduce the number of transactions that need to be further evaluated as business combinations. If further evaluation is necessary, the updated guidance will require that a business set include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output. The updated guidance will remove the evaluation of whether a market participant could replace missing elements. The new guidance is effective for annual and interim periods beginning after December 15, 2017 and is to be applied on a prospective basis. The Company adopted the new guidance on January 1, 2018 and it will be applied to business combinations on a prospective basis. Compensation — — — I n March 2016, the FASB issued updated guidance on the presentation of net benefit cost in the statement of operations and the components eligible for capitalization. The new guidance requires that only the service cost component of net periodic pension cost and net periodic postretirement benefit cost be presented with other employee compensation costs in operating expenses, applied on a retrospective basis. The other components of net benefit cost, including amortization of prior service cost, and gains and losses from settlements and curtailments, are included in other operating expenses. The new guidance also stipulates that only the service cost component of net benefit cost is eligible for capitalization, applied on a prospective basis. This new guidance is effective for annual and interim periods beginning after December 15, 2017. The Company adopted the new guidance on January 1, 2018 and there was no material impact to the Company’s financial statements. Compensation—Stock Compensation: Scope of Modification Accounting— In May 2017, the FASB issued updated guidance on modifications to share-based payment awards. The updated guidance requires entities to account for the effects of a modification to a share-based payment award unless the following are all the same immediately before and after the modification: (i) the fair value of the award, (ii) the vesting conditions of the award, and (iii) the classification of the award as an equity instrument or a liability instrument. This new guidance is effective for annual and interim periods beginning after December 15, 2017 and is to be applied on a prospective basis. The Company adopted the new guidance on January 1, 2018, and there was no material impact to the Company’s financial statements. Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income— In February 2018, the FASB issued updated guidance on the tax effects of items in “accumulated other comprehensive income (loss), net of tax” (“AOCI”). Specifically, the new guidance will permit, but not require, a reclassification from AOCI to retained earnings for stranded tax effects resulting from the newly enacted federal corporate income tax rate under the Tax Cuts and Jobs Act of 2017 (see Note 15). The amount of the reclassification would be the difference between the historical corporate income tax rate and the newly enacted 21% corporate income tax rate. The new guidance is effective for annual and interim periods beginning after December 15, 2018, with an option to apply it in the period of adoption or on a retrospective basis for each period in which the effect of the change in the U.S. federal corporate income tax rate is recognized. Early adoption of the new guidance is permitted for public business entities for reporting periods for which financial statements have not yet been issued. The Company is currently evaluating the new guidance. Leases —In February 2016, the FASB issued updated guidance for leases. The guidance requires a lessee to (i) recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in the statement of financial condition, (ii) recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term on a generally straight-line basis, and (iii) classify all cash payments within operating activities in the statement of cash flows. The new guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. The new guidance is to be applied on a modified retrospective basis. The Company is currently evaluating the new guidance. Improvements to Nonemployee Share-Based Payment Accounting— In June 2018, the FASB issued updated guidance to simplify the accounting for nonemployee share-based payment transactions. The new guidance generally requires equity-classified nonemployee share-based payment awards to be measured at the grant date, which is the date at which a grantor and grantee reach a mutual understanding of the key terms and conditions of a share-based payment award. This update generally aligns the accounting for equity-classified share-based payment awards to nonemployees with the measurement date required for employees. The new guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. Upon adoption, the new guidance would be applied on a modified retrospective basis. The Company is currently evaluating the new guidance. Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments —In June 2016, the FASB issued new guidance regarding the measurement of credit losses on financial instruments. The new guidance replaces the incurred loss impairment methodology in the current guidance with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The new guidance is effective for annual and interim periods beginning after December 15, 2019 with early adoption permitted for fiscal years beginning after December 15, 2018. The Company is currently evaluating the new guidance. Intangibles—Goodwill and Other: Simplifying the Test for Goodwill Impairment —In January 2017, the FASB issued updated guidance which eliminated Step 2 from the goodwill impairment test. Step 2 is the process of measuring a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The new guidance requires entities to measure a goodwill impairment loss as the amount by which a reporting unit’s carrying value exceeds its fair value, limited to the carrying amount of goodwill. The FASB also eliminated the requirements for entities that have reporting units with zero or negative carrying amounts to perform a qualitative assessment for the goodwill impairment test. Instead, those entities would be required to disclose the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount. The new guidance is effective for interim or annual goodwill impairment tests performed in fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the new guidance.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2018
Revenue Recognition [Abstract]
Revenue Recognition	3. REVENUE RECOGNITION Investment Banking and Other Advisory —Fees for Financial Advisory services are recorded when: (i) a contract with a client has been identified, (ii) the performance obligations in the contract have been identified, (iii) the fee or other transaction price has been determined; (iv) the fee or other transaction price has been allocated to each performance obligation in the contract; and (v) the Company has satisfied the applicable performance obligation. The expenses that are directly related to such transactions are recorded as incurred and presented within operating expenses when the Company is primarily responsible for fulfilling the promise of the arrangement. Revenues associated with the reimbursement of such expenses are recorded when the Company is contractually entitled to reimbursement and presented within investment banking and other advisory fees. Asset Management Fees —Fees for Asset Management services are primarily comprised of management fees and incentive fees. Management fees are derived from fees for investment management and other services provided to clients. Revenue is recorded in accordance with the same five criteria as Financial Advisory fees, which generally results in management fees being recorded on a daily, monthly or quarterly basis, primarily based on a percentage of client assets managed. Fees vary with the type of assets managed, with higher fees earned on equity assets, alternative investment (such as hedge fund) and private equity funds, and lower fees earned on fixed income and money market products. Expenses that are directly related to the sale or distribution of fund interests are recorded as incurred and presented within operating expenses when the Company is primarily responsible for fulfilling the promise of the arrangement. Revenues associated with the reimbursement of such expenses are recorded when the Company is contractually entitled to reimbursement and presented within asset management fees. In addition, the Company earns performance-based incentive fees on various investment products, including traditional products and alternative investment funds such as hedge funds and private equity funds. For hedge funds, incentive fees are calculated based on a specific percentage of a fund’s net appreciation, in some cases in excess of established benchmarks or thresholds. The Company records incentive fees on traditional products and hedge funds when a significant reversal in the amount of the cumulative revenue to be recognized is not probable, which is typically at the end of the relevant performance measurement period. The incentive fee measurement period is generally an annual period (unless an account is terminated during the year). The incentive fees received at the end of the measurement period are not subject to reversal or payback. Incentive fees on hedge funds generally are subject to loss carryforward provisions in which losses incurred by the hedge funds in any year are applied against certain gains realized by the hedge funds in future periods before any incentive fees can be earned. For private equity funds, incentive fees may be earned in the form of a “carried interest” if profits arising from realized investments exceed a specified threshold. Typically, such carried interest is ultimately calculated on a whole-fund basis and, therefore, clawback of carried interests during the life of the fund can occur. As a result, the Company records incentive fees earned on our private equity funds when a significant reversal in the amount of the cumulative revenue to be recognized is not probable, which is typically at the end of the relevant performance period. Receivables relating to asset management and incentive fees are reported in “fees receivable” on the consolidated statements of financial condition. The Company disaggregates revenue based on its business segment results and believes that the following information provides a reasonable representation of how performance obligations relate to the nature, amount, timing and uncertainty of revenue and cash flows: Three Months Ended Six Months Ended June 30, 2018 (d) June 30, 2018 (d) Net Revenue: Financial Advisory (a) $ 419,468 $ 827,935 Asset Management: Management Fees and Other (b) $ 340,160 $ 688,844 Incentive Fees (c) 12,428 18,027 Total Asset Management $ 352,588 $ 706,871 (a) Financial Advisory is comprised of M&A Advisory, Capital Advisory, Capital Raising, Restructuring, Shareholder Advisory, Sovereign Advisory, and other strategic advisory work for clients. The benefits of these advisory services are generally transferred to the Company’s clients over time, and consideration for these advisory services typically includes transaction completion, transaction announcement and retainer fees. Retainer fees are generally fixed and recognized over the period in which the advisory services are performed. However, transaction announcement and transaction completion fees are variable and subject to constraints, and they are typically not recognized until there is an announcement date or a completion date, respectively, due to the uncertainty associated with those events. The advisory fees that may be unrecognized as of the end of a reporting period, primarily comprised of fees associated with transaction announcements and transaction completions, generally remain unrecognized due to the uncertainty associated with those events. (b) Management fees and other is primarily comprised of management services. The benefits of these management services are transferred to the Company’s clients over time. Consideration for these management services generally includes management fees, which are based on assets under management and recognized over the period in which the management services are performed. The selling or distribution of fund interests is a separate performance obligation within management fees and other, and the benefits of such services are transferred to the Company’s clients at the point in time that such fund interests are sold or distributed. (c) Incentive fees is primarily comprised of management services. The benefits of these management services are transferred to the Company’s clients over time. Consideration for these management services is generally variable and includes performance or incentive fees. The fees allocated to these management services that are unrecognized as of the end of the reporting period are generally amounts that are subject to constraints due to the uncertainty associated with performance targets and clawbacks. ( d ) In addition to the above, contracts with clients include trade-based commission income, which is recognized at the point in time of execution and presented within other revenue. Such income may be earned by providing trade facilitation, execution, clearance and settlement, custody, and trade administration services to clients. With regard to the disclosure requirement for remaining performance obligations, the Company elected the practical expedients permitted in the guidance to (i) exclude contracts with a duration of one year or less; and (ii) exclude variable consideration, such as transaction completion and transaction announcement fees, that is allocated entirely to unsatisfied performance obligations. Excluded variable consideration typically relates to contracts with a duration of one year or less, and is generally constrained due to uncertainties. Therefore, when applying the practical expedients, amounts related to remaining performance obligations are not material to the Company’s financial statements.

Receivables

Receivables	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Receivables	4. RECEIVABLES The Company’s receivables represent fee receivables, amounts due from customers and other receivables, and amounts due from Lazard Ltd subsidiaries. Receivables are stated net of an estimated allowance for doubtful accounts, for past due amounts and for specific accounts deemed uncollectible, which may include situations where a fee is in dispute. Activity in the allowance for doubtful accounts for the three month and six month periods ended June 30, 2018 and 2017 was as follows: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Beginning Balance $ 38,505 $ 29,662 $ 23,692 $ 16,386 Bad debt expense, net of recoveries 666 180 16,618 13,831 Charge-offs, foreign currency translation and other adjustments (4,265 ) (4,748 ) (5,404 ) (5,123 ) Ending Balance $ 34,906 $ 25,094 $ 34,906 $ 25,094 Bad debt expense, net of recoveries is included in “operating expenses — At June 30, 2018 and December 31, 2017, the Company had receivables past due or deemed uncollectible of $42,384 and $34,865, respectively. Of the Company’s fee receivables at June 30, 2018 and December 31, 2017, $74,668 and $80,536, respectively, represented interest-bearing financing receivables. In addition, at June 30, 2018 and December 31, 2017, the Company had interest-bearing receivables from Lazard Ltd subsidiaries of $83,069 and $72, respectively. 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 $662,784 and $508,143 at June 30, 2018 and December 31, 2017, respectively, approximates fair value.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments Schedule [Abstract]
Investments	5. INVESTMENTS The Company’s investments and securities sold, not yet purchased, consist of the following at June 30, 2018 and December 31, 2017: June 30, December 31, 2018 2017 Interest-bearing deposits $ 530 $ 556 Debt 74,583 6 Equities 39,818 45,257 Funds: Alternative investments (a) 26,097 20,993 Debt (a) 87,529 84,077 Equity (a) 209,379 199,618 Private equity 67,258 76,679 390,263 381,367 Total investments 505,194 427,186 Less: Interest-bearing deposits 530 556 Investments, at fair value $ 504,664 $ 426,630 Securities sold, not yet purchased, at fair value (included in “other liabilities”) $ 4,419 $ 7,338 (a) Interests in alternative investment funds, debt funds and equity funds include investments with fair values of $11,898, $57,444 and $147,862, respectively, at June 30, 2018 and $11,213, $48,391 and $131,893, respectively, at December 31, 2017, held in order to satisfy the Company’s liability upon vesting of previously granted Lazard Fund Interests (“LFI”) and other similar deferred compensation arrangements. LFI represent grants by the Company to eligible employees of actual or notional interests in a number of Lazard-managed funds, subject to service-based vesting conditions (see Notes 7 and 13). Interest-bearing deposits have original maturities of greater than three months but equal to or less than one year and are carried at cost that approximates fair value due to their short-term maturities. Debt primarily consists of U.S. Treasury securities with original maturities of greater than three months and less than one year. 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. Alternative investment funds primarily consist of interests in various Lazard-managed hedge funds, funds of funds and mutual funds. Such amounts primarily consist of seed investments in funds related to our Asset Management business and amounts related to LFI discussed above. Debt funds primarily consist of seed investments in funds related to our Asset Management business that invest in debt securities, amounts related to LFI discussed above and an investment in a Lazard-managed debt fund. Equity funds primarily consist of seed investments in funds related to our Asset Management business that invest in equity securities, and amounts related to LFI 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) Edgewater Growth Capital Partners III, L.P. (“EGCP III”), a fund primarily making equity and buyout investments in middle market companies, (ii) a fund targeting significant noncontrolling-stake investments in established private companies and (iii) until the second quarter of 2017, a mezzanine fund (the “Mezzanine Fund”), which invests in mezzanine debt of a diversified selection of small- to mid-cap European companies. Lazard sold its interest in the Mezzanine Fund in May 2017. 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”). During the three month and six month periods ended June 30, 2018 and 2017, the Company reported in “revenue-other” on its condensed consolidated statements of operations net unrealized investment gains and losses pertaining to “trading” securities still held as of the reporting date as follows: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Net unrealized investment gains (losses) $ (5,864 ) $ 7,803 $ (15,155 ) $ 20,983

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. FAIR VALUE MEASUREMENTS Fair Value Hierarchy of Investments and Certain Other Assets and Liabilities —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, or (ii) 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. 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, debt funds and equity funds is classified as Level 1 when the fair values are primarily based on the publicly reported closing price for the fund. The fair value of securities sold, not yet purchased, is classified as Level 1 when the fair values are based on unadjusted quoted prices in active markets. The fair value of the contingent consideration liability is classified as Level 3 and the fair value of the liability is remeasured at each reporting period. The inputs used to derive the fair value of the contingent consideration include the application of probabilities when assessing certain performance thresholds for the relevant periods. The fair value of derivatives entered into by the Company is classified as Level 2 and is 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 total return swaps is based on the change in fair value 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 LFI and other similar deferred compensation arrangements is based on the value of the underlying investments, adjusted for forfeitures. See Note 7. Investments Measured at Net Asset Value (“NAV”) —As a practical expedient, the Company uses NAV or its equivalent to measure the fair value of certain investments. NAV is primarily determined based on information provided by external fund administrators. The Company’s investments valued at NAV as a practical expedient in (i) alternative investment funds, debt funds and equity funds are redeemable in the near term, and (ii) private equity funds are not redeemable in the near term as a result of redemption restrictions. The following tables present, as of June 30, 2018 and December 31, 2017, the classification of (i) investments and certain other assets and liabilities measured at fair value on a recurring basis within the fair value hierarchy and (ii) investments measured at NAV or its equivalent as a practical expedient: June 30, 2018 Level 1 Level 2 Level 3 NAV Total Assets: Investments: Debt $ 74,583 $ - $ - $ - $ 74,583 Equities 38,189 - 1,629 - 39,818 Funds: Alternative investments 25,168 - - 929 26,097 Debt 87,522 - - 7 87,529 Equity 209,326 - - 53 209,379 Private equity - - - 67,258 67,258 Derivatives - 6,399 - - 6,399 Total $ 434,788 $ 6,399 $ 1,629 $ 68,247 $ 511,063 Liabilities: Securities sold, not yet purchased $ 4,419 $ - $ - $ - $ 4,419 Contingent consideration liability 3,470 - 3,470 Derivatives - 202,975 - - 202,975 Total $ 4,419 $ 202,975 $ 3,470 $ - $ 210,864 December 31, 2017 Level 1 Level 2 Level 3 NAV Total Assets: Investments: Debt $ 6 $ - $ - $ - $ 6 Equities 43,665 - 1,592 - 45,257 Funds: Alternative investments 17,353 - - 3,640 20,993 Debt 84,071 - - 6 84,077 Equity 199,565 - - 53 199,618 Private equity - - - 76,679 76,679 Derivatives - 3,732 - - 3,732 Total $ 344,660 $ 3,732 $ 1,592 $ 80,378 $ 430,362 Liabilities: Securities sold, not yet purchased $ 7,338 $ - $ - $ - $ 7,338 Contingent consideration liability - - 4,656 - 4,656 Derivatives - 198,417 - - 198,417 Total $ 7,338 $ 198,417 $ 4,656 $ - $ 210,411 The following tables provide a summary of changes in fair value of the Company’s Level 3 assets and liabilities for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended June 30, 2018 Beginning Balance Net Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,599 $ 62 $ - $ - $ (32 ) $ 1,629 Total Level 3 Assets $ 1,599 $ 62 $ - $ - $ (32 ) $ 1,629 Liabilities: Contingent consideration liability $ 4,661 $ (1,191 ) $ - $ - $ - $ 3,470 Total Level 3 Liabilities $ 4,661 $ (1,191 ) $ - $ - $ - $ 3,470 Six Months Ended June 30, 2018 Beginning Balance Net Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,592 $ 61 $ 1 $ - $ (25 ) $ 1,629 Total Level 3 Assets $ 1,592 $ 61 $ 1 $ - $ (25 ) $ 1,629 Liabilities: Contingent consideration liability $ 4,656 $ (1,186 ) $ - $ - $ - $ 3,470 Total Level 3 Liabilities $ 4,656 $ (1,186 ) $ - $ - $ - $ 3,470 Three Months Ended June 30, 2017 Beginning Balance Net Unrealized/ Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,537 $ (128 ) $ 1,661 $ - $ 2 $ 3,072 Total Level 3 Assets $ 1,537 $ (128 ) $ 1,661 $ - $ 2 $ 3,072 Liabilities: Contingent consideration liability $ 4,078 $ 30 $ - $ - $ - $ 4,108 Total Level 3 Liabilities $ 4,078 $ 30 $ - $ - $ - $ 4,108 Six Months Ended June 30, 2017 Beginning Balance Net Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,508 $ (126 ) $ 1,661 $ (8 ) $ 37 $ 3,072 Total Level 3 Assets $ 1,508 $ (126 ) $ 1,661 $ (8 ) $ 37 $ 3,072 Liabilities: Contingent consideration liability $ 3,364 $ 744 $ - $ - $ - $ 4,108 Total Level 3 Liabilities $ 3,364 $ 744 $ - $ - $ - $ 4,108 (a) Earnings recorded in “other revenue” for investments in equities for the three month and six month periods ended June 30, 2018 and the three month and six month periods ended June 30, 2017 include net unrealized gains (losses) of $62, $61, $(128) and $(128), respectively. Earnings recorded in “amortization and other acquisition-related (benefits) costs” for the contingent consideration liability for the three month and six month periods ended June 30, 2018 and the three month and six month periods ended June 30, 2017 include unrealized (gains) losses of $(1,191), $(1,186), $30 and $744, respectively. 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 six month periods ended June 30, 2018 and 2017. The following tables present, at June 30, 2018 and December 31, 2017, certain investments that are valued using NAV or its equivalent as a practical expedient in determining fair value: June 30, 2018 Estimated Liquidation Period of Investments Not Redeemable Investments Redeemable Fair Value Unfunded Commitments % of Fair Value Not Redeemable % Next 5 Years % 5-10 Years % Thereafter Redemption Frequency Redemption Notice Period Alternative Hedge funds $ 332 $ - NA NA NA NA (a) 60 days Funds of funds 25 - NA NA NA NA (b) 90 days Other 572 - NA NA NA NA (c) <30-60 days Debt funds 7 - NA NA NA NA (d) 30 days Equity funds 53 - NA NA NA NA (e) <30-90 days Private equity funds: Equity growth 67,258 8,650 (f) 100 % 18 % 39 % 43 % NA NA Total $ 68,247 $ 8,650 (a) monthly (100%) (b) quarterly (100%) (c) daily (6%) and monthly (94%) (d) daily (100%) (e) daily (19%), monthly (49%) and quarterly (32%) (f) Unfunded commitments to private equity investments consolidated but not owned by Lazard of $15,517 are excluded. Such commitments are required to be funded by capital contributions from noncontrolling interest holders. December 31, 2017 Estimated Liquidation Period of Investments Not Redeemable Investments Redeemable Fair Value Unfunded Commitments % of Fair Value Not Redeemable % Next 5 Years % 5-10 Years % Thereafter Redemption Frequency Redemption Notice Period Alternative Hedge funds $ 2,517 $ - NA NA NA NA (a) <30-60 days Funds of funds 528 - NA NA NA NA (b) <30-90 days Other 595 - NA NA NA NA (c) <30-60 days Debt funds 6 - NA NA NA NA (d) 30 days Equity funds 53 - NA NA NA NA (e) <30-90 days Private equity funds: Equity growth 76,679 10,300 (f) 100 % 16 % 38 % 46 % NA NA Total $ 80,378 $ 10,300 (a) weekly (3%), monthly (5%) and quarterly (92%) (b) monthly (97%) and quarterly (3%) (c) daily (6%) and monthly (94%) (d) daily (100%) (e) daily (18%), monthly (50%) and quarterly (32%) (f) Unfunded commitments to private equity investments consolidated but not owned by Lazard of $5,902 are excluded. Such commitments are required to be funded by capital contributions from noncontrolling interest holders. Investment Capital Funding Commitments —At June 30, 2018, the Company’s maximum unfunded commitments for capital contributions to investment funds primarily arose from commitments to EGCP III, which amounted to $7,847. The investment period for EGCP III ended on October 12, 2016, after which point the Company’s obligation to fund capital contributions for new investments in EGCP III expired. The Company remains obligated until October 12, 2023 (or any earlier liquidation of EGCP III) to make capital contributions necessary to fund follow-on investments and to pay for fund expenses.

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivatives	7. DERIVATIVES The Company enters into forward foreign currency exchange rate contracts, interest rate swaps, interest rate futures, total return swap contracts on various equity and debt indices and other derivative contracts to economically 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 condensed consolidated statements of financial condition. Gains and losses on the Company’s derivative instruments are generally included in “interest income” and “interest expense”, respectively, or “revenue-other”, depending on the nature of the underlying item, in the condensed consolidated statements of operations. In addition to the derivative instruments described above, the Company records derivative liabilities relating to its obligations pertaining to LFI 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 condensed consolidated statements of financial condition. Changes in the fair value of the derivative liabilities are included in “compensation and benefits” in the condensed 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 LFI and other similar deferred compensation arrangements, which are reported in “revenue-other” in the condensed consolidated statements of operations. The table below presents the fair value of the Company’s derivative instruments reported within “other assets” and “other liabilities” and the fair value of the Company’s derivative liabilities relating to its obligations pertaining to LFI and other similar deferred compensation arrangements reported within “accrued compensation and benefits” (see Note 13) on the accompanying condensed consolidated statements of financial condition as of June 30, 2018 and December 31, 2017: June 30, December 31, 2018 2017 Derivative Assets: Forward foreign currency exchange rate contracts $ 1,193 $ 3,314 Total return swaps and other (a) 5,206 418 $ 6,399 $ 3,732 Derivative Liabilities: Forward foreign currency exchange rate contracts $ 2,122 $ 4,846 Total return swaps and other (a) 9 11,270 LFI and other similar deferred compensation arrangements 200,844 182,301 $ 202,975 $ 198,417 (a) For total return swaps, amounts represent the netting of gross derivative assets and liabilities of $5,789 and $592 as of June 30, 2018, respectively, and $469 and $11,321 as of December 31, 2017, 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 $1,216 and $17,616 as of June 30, 2018 and December 31, 2017, 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 LFI 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 six month periods ended June 30, 2018 and 2017, were as follows: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Forward foreign currency exchange rate contracts $ 6,236 $ (6,630 ) $ 3,753 $ (5,158 ) LFI and other similar deferred compensation arrangements 499 (5,753 ) 1,935 (13,106 ) Total return swaps and other 790 (3,597 ) 2,446 (8,982 ) Total $ 7,525 $ (15,980 ) $ 8,134 $ (27,246 )

Property

Property	6 Months Ended
	Jun. 30, 2018
Property Plant And Equipment [Abstract]
Property	8. PROPERTY At June 30, 2018 and December 31, 2017, property consisted of the following: Estimated Depreciable June 30, December 31, Life in Years 2018 2017 Buildings 33 $ 147,669 $ 151,912 Leasehold improvements 3-20 185,680 173,102 Furniture and equipment 3-10 192,752 183,510 Construction in progress 13,497 13,120 Total 539,598 521,644 Less - Accumulated depreciation and amortization 324,863 317,816 Property $ 214,735 $ 203,828

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	9. GOODWILL AND OTHER INTANGIBLE ASSETS The components of goodwill and other intangible assets at June 30, 2018 and December 31, 2017 are presented below: June 30, December 31, 2018 2017 Goodwill $ 355,933 $ 362,760 Other intangible assets (net of accumulated amortization) 4,754 5,274 $ 360,687 $ 368,034 At June 30, 2018 and December 31, 2017, goodwill of $291,392 and $298,219, 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 six month periods ended June 30, 2018 and 2017 are as follows: Six Months Ended June 30, 2018 2017 Balance, January 1 $ 362,760 $ 352,124 Foreign currency translation adjustments (6,827 ) 7,968 Balance, June 30 $ 355,933 $ 360,092 All changes in the carrying amount of goodwill for the six month periods ended June 30, 2018 and 2017 are attributable to the Company’s Financial Advisory segment. The gross cost and accumulated amortization of other intangible assets as of June 30, 2018 and December 31, 2017, by major intangible asset category, are as follows: June 30, 2018 December 31, 2017 Gross Cost Accumulated Amortization Net Carrying Amount Gross Cost Accumulated Amortization Net Carrying Amount Success/incentive fees $ 33,040 $ 29,060 $ 3,980 $ 33,040 $ 27,927 $ 5,113 Management fees, customer relationships and non-compete agreements 34,186 33,412 774 33,436 33,275 161 $ 67,226 $ 62,472 $ 4,754 $ 66,476 $ 61,202 $ 5,274 Amortization expense of intangible assets, included in “amortization and other acquisition-related (benefits) costs” in the condensed consolidated statements of operations, for the three month and six month periods ended June 30, 2018 was $653 and $1,270, respectively, and for the three month and six month periods ended June 30, 2017 was $433 and $867, respectively. Estimated future amortization expense is as follows: Year Ending December 31, Amortization Expense (a) 2018 (July 1 through December 31) $ 1,120 2019 1,648 2020 1,648 2021 150 2022 150 2023 38 Total amortization expense $ 4,754 (a) Approximately 37% of intangible asset amortization is attributable to a noncontrolling interest.

Senior Debt

Senior Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Senior Debt	10. SENIOR DEBT Senior debt is comprised of the following as of June 30, 2018 and December 31, 2017: Outstanding as of Initial Annual June 30, 2018 December 31, 2017 Principal Amount Maturity Date Interest Rate(a) Principal Unamortized Debt Costs Carrying Value Principal Unamortized Debt Costs Carrying Value Lazard Group 2020 Senior Notes $ 500,000 11/14/20 4.25 % $ 500,000 $ 2,187 $ 497,813 $ 500,000 $ 2,647 $ 497,353 Lazard Group 2025 Senior Notes 400,000 2/13/25 3.75 % 400,000 3,124 396,876 400,000 3,361 396,639 Lazard Group 2027 Senior Notes 300,000 3/1/27 3.625 % 300,000 3,412 296,588 300,000 3,609 296,391 Total $ 1,200,000 $ 8,723 $ 1,191,277 $ 1,200,000 $ 9,617 $ 1,190,383 (a) The effective interest rates of Lazard Group’s 4.25% senior notes due November 14, 2020 (the “2020 Notes”), Lazard Group’s 3.75% senior notes due February 13, 2025 (the “2025 Notes”) and Lazard Group’s 3.625% senior notes due March 1, 2027 (the “2027 Notes”) are 4.43%, 3.87% and 3.76%, respectively. On September 25, 2015, Lazard Group entered into an Amended and Restated Credit Agreement for a five-year $150,000 senior revolving credit facility with a group of lenders (the “Amended and Restated Credit Agreement”), which expires in September 2020. The Amended and Restated Credit Agreement amended and restated the previous credit agreement dated September 25, 2012. Borrowings under the Amended and Restated Credit Agreement generally will bear interest at LIBOR plus an applicable margin for specific interest periods determined based on Lazard Group’s highest credit rating from an internationally recognized credit agency. At June 30, 2018 and December 31, 2017, no amounts were outstanding under the Amended and Restated Credit Agreement. The Amended and Restated Credit Agreement, 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 June 30, 2018, the Company was in compliance with such provisions. All of the Company’s senior debt obligations are unsecured. As of June 30, 2018, the Company had approximately $169,000 in unused lines of credit available to it, including the credit facility provided under the Amended and Restated Credit Agreement and unused lines of credit available to LFB of approximately $17,000 (at June 30, 2018 exchange rates). The Company’s senior debt at June 30, 2018 and December 31, 2017 is carried at historical amounts of $1,191,277 and $1,190,383, respectively. At those dates, the fair value of such senior debt was approximately $1,183,000 and $1,230,000, respectively. The fair value of the Company’s senior debt is 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	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. COMMITMENTS AND CONTINGENCIES Leases —The Company has various leases and other contractual commitments arising in the ordinary course of business. 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 June 30, 2018, LFB had $2,750 of such indemnifications and held $2,750 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. Business Acquisitions —For a business acquired in 2016, the remaining consideration consists of (i) 60,817 shares of Class A common stock subject to non-compete provisions, and (ii) up to 210,431 additional shares of Class A common stock that are subject to certain performance thresholds. As of June 30, 2018, none of the contingent shares had been earned. Other Commitments —The Company has various other contractual commitments arising in the ordinary course of business. In addition, from time to time, each of LFB and LFNY may enter into underwriting commitments in which it will participate as an underwriter. At June 30, 2018, LFB and LFNY had no such underwriting commitments. See Notes 6 and 14 for information regarding commitments relating to investment capital funding commitments and obligations to fund our pension plans, respectively. In the opinion of management, the fulfillment of the commitments described herein will not have a material adverse effect on the Company’s condensed 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.

Members' Equity

Members' Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Members' Equity	12. MEMBERS’ EQUITY Lazard Group Distributions —Distributions in respect of Lazard Group’s common membership interests are allocated to the holders of such interests in accordance with the provisions of the Operating Agreement. Such distributions primarily 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 incur. During the six month periods ended June 30, 2018 and 2017, Lazard Group distributed $265,592 and $244,722, respectively, to the subsidiaries of Lazard Ltd. 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. Share Repurchase Program —During the six month period ended June 30, 2018 and since 2015, the Board of Directors of Lazard authorized the repurchase of Lazard Ltd Class A common stock as set forth in the table below: Date Repurchase Authorization Expiration February 2015 $ 150,000 December January 2016 $ 200,000 December April 2016 $ 113,182 December November 2016 $ 236,000 December October 2017 $ 200,000 December April 2018 $ 300,000 December 31, 2020 The Company expects that the share repurchase program will primarily be used to offset a portion of the shares that have been or will be issued under the Lazard Ltd 2008 Incentive Compensation Plan (the “2008 Plan”) and the Lazard Ltd 2018 Incentive Compensation Plan (the “2018 Plan”). Pursuant to the share repurchase program, purchases have been made in the open market or through privately negotiated transactions. The rate at which the Company purchases shares in connection with the share repurchase program may vary from quarter to quarter due to a variety of factors. Purchases with respect to such program are set forth in the table below: Six Months Ended June 30: Number of Shares Purchased Average Price Per Share 2017 4,268,479 $ 43.32 2018 4,147,526 $ 53.96 During the six month periods ended June 30, 2018 and 2017, certain of our executive officers received Lazard Ltd Class A common stock in connection with the vesting or settlement of previously-granted deferred equity incentive awards. The vesting or settlement of such equity awards gave rise to a tax payable by the executive officers, and, consistent with our past practice, the Company purchased shares of Lazard Ltd Class A common stock from the executive officers equal in value to all or a portion of the estimated amount of such tax. In addition, during the six month periods ended June 30, 2018 and 2017, the Company purchased shares of Lazard Ltd Class A common stock from certain of our executive officers. The aggregate value of all such purchases during the six month periods ended June 30, 2018 and 2017 was approximately $16,400 and $14,700, respectively. As of June 30, 2018, a total of $324,589 of share repurchase authorization remained available under Lazard Ltd’s share repurchase program, of which $24,589 will expire on December 31, 2019 and $300,000 will expire on December 31, 2020. During the six month period ended June 30, 2018, Lazard Ltd had in place trading plans under Rule 10b5-1 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), pursuant to which it effected stock repurchases in the open market. Accumulated Other Comprehensive Income (Loss), Net of Tax —The tables below reflect the balances of each component of AOCI at June 30, 2018 and 2017 and activity during the three month and six month periods then ended: Three Months Ended June 30, 2018 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, April 1, 2018 $ (24,841 ) $ (155,418 ) $ (180,259 ) $ - $ (180,259 ) Activity: Other comprehensive income (loss) before reclassifications (40,576 ) 8,300 (32,276 ) (1 ) (32,275 ) Adjustments for items reclassified to earnings, net of tax - 777 777 - 777 Net other comprehensive income (loss) (40,576 ) 9,077 (31,499 ) (1 ) (31,498 ) Balance, June 30, 2018 $ (65,417 ) $ (146,341 ) $ (211,758 ) $ (1 ) $ (211,757 ) Six Months Ended June 30, 2018 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, January 1, 2018 $ (43,790 ) $ (151,466 ) $ (195,256 ) $ - $ (195,256 ) Activity: Other comprehensive income (loss) before reclassifications (21,627 ) 3,286 (18,341 ) (1 ) (18,340 ) Adjustments for items reclassified to earnings, net of tax - 1,839 1,839 - 1,839 Net other comprehensive income (loss) (21,627 ) 5,125 (16,502 ) (1 ) (16,501 ) Balance, June 30, 2018 $ (65,417 ) $ (146,341 ) $ (211,758 ) $ (1 ) $ (211,757 ) Three Months Ended June 30, 2017 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, April 1, 2017 $ (96,007 ) $ (160,880 ) $ (256,887 ) $ (2 ) $ (256,885 ) Activity: Other comprehensive income (loss) before reclassifications 25,323 (8,609 ) 16,714 1 16,713 Adjustments for items reclassified to earnings, net of tax - 1,356 1,356 - 1,356 Net other comprehensive income (loss) 25,323 (7,253 ) 18,070 1 18,069 Balance, June 30, 2017 $ (70,684 ) $ (168,133 ) $ (238,817 ) $ (1 ) $ (238,816 ) Six Months Ended June 30, 2017 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, January 1, 2017 $ (109,306 ) $ (161,471 ) $ (270,777 ) $ (2 ) $ (270,775 ) Activity: Other comprehensive income (loss) before reclassifications 38,622 (9,104 ) 29,518 1 29,517 Adjustments for items reclassified to earnings, net of tax - 2,442 2,442 - 2,442 Net other comprehensive income (loss) 38,622 (6,662 ) 31,960 1 31,959 Balance, June 30, 2017 $ (70,684 ) $ (168,133 ) $ (238,817 ) $ (1 ) $ (238,816 ) The table below reflects adjustments for items reclassified out of AOCI, by component, for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Amortization relating to employee benefit plans (a) $ 1,245 $ 1,552 $ 2,523 $ 2,914 Less - related income taxes 468 196 684 472 Total reclassifications, net of tax $ 777 $ 1,356 $ 1,839 $ 2,442 ( a ) Included in the computation of net periodic benefit cost (see Note 14). Such amounts are included in “operating expenses — Noncontrolling Interests —Noncontrolling interests principally represent interests held in Edgewater’s management vehicles that the Company is deemed to control, but does not own. The tables below summarize net income attributable to noncontrolling interests for the three month and six month periods ended June 30, 2018 and 2017 and noncontrolling interests as of June 30, 2018 and December 31, 2017 in the Company’s condensed consolidated financial statements: Net Income Attributable to Noncontrolling Interests Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Edgewater $ 1,415 $ 520 $ 3,383 $ 3,397 Other 1 2 2 2 Total $ 1,416 $ 522 $ 3,385 $ 3,399 Noncontrolling Interests as of June 30, December 31, 2018 2017 Edgewater $ 57,386 $ 58,568 Other 11 14 Total $ 57,397 $ 58,582

Incentive Plans

Incentive Plans	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Incentive Plans	13. INCENTIVE PLANS Share-Based Incentive Plan Awards A description of Lazard Ltd’s 2018 Plan, 2008 Plan and 2005 Equity Incentive Plan (the “2005 Plan”) and activity with respect thereto during the three month and six month periods ended June 30, 2018 and 2017 is presented below. Shares Available Under the 2018 Plan, 2008 Plan and 2005 Plan The 2018 Plan became effective on April 24, 2018 and replaced the 2008 Plan, which was terminated on April 24, 2018. The 2018 Plan authorizes the issuance of up to 30,000,000 shares of Class A common stock pursuant to the grant or exercise of stock options, stock appreciation rights, restricted stock units (“RSUs”), performance-based restricted stock units (“PRSUs”) and other share-based awards. The 2008 Plan authorized the issuance of shares of Class A common stock pursuant to the grant or exercise of stock options, stock appreciation rights, RSUs, PRSUs and other share-based awards. Under the 2008 Plan, the maximum number of shares available was based on a formula that limited the aggregate number of shares that could, at any time, be subject to awards that were considered “outstanding” under the 2008 Plan to 30% of the then-outstanding shares of Class A common stock. The 2008 Plan was terminated on April 24, 2018, and no additional awards have been or will be granted under the 2008 Plan after its termination, although unvested awards granted under the 2008 Plan before its termination remain outstanding and continue to be subject to its terms. The 2005 Plan authorized 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 share-based awards. The 2005 Plan expired in the second quarter of 2015, although unvested deferred stock unit (“DSU”) awards granted under the 2005 Plan before its expiration remain outstanding and continue to be subject to its terms. 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 DSUs) within the Company’s accompanying condensed consolidated statements of operations for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Share-based incentive awards: RSUs $ 55,635 $ 54,354 $ 116,522 $ 110,295 PRSUs 17,051 16,417 28,018 28,199 Restricted Stock 12,600 13,161 23,373 22,810 DSUs 863 771 959 848 Total $ 86,149 $ 84,703 $ 168,872 $ 162,152 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, including as a result of any applicable performance conditions. A change in estimated forfeiture rates or performance results in a cumulative adjustment to 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. The Company’s share-based incentive plans and awards 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 shares of Class A common stock on a one-for-one basis after the stipulated vesting periods. PRSUs, which are RSUs that are also subject to service-based vesting conditions, have additional performance 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 period. 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 dividends paid on Class A common stock during such period. During the six month periods ended June 30, 2018 and 2017, dividend participation rights required the issuance of 636,207 and 739,079 RSUs, respectively. Non-executive members of the Board of Directors of Lazard Group, who are the same Non-Executive Directors of Lazard Ltd (“Non-Executive 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 30,463 and 31,280 DSUs granted during the six month periods ended June 30, 2018 and 2017, 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 shares of Class A common stock at the time of cessation of service to the Board of Directors. DSUs include a cash dividend participation right equivalent to dividends paid on Class A common stock. The Company’s Directors’ Fee Deferral Unit Plan permits the Non-Executive Directors to elect to receive additional DSUs in lieu of some or all of their cash fees. The number of DSUs 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 immediately preceding the date of the grant. During the six month periods ended June 30, 2018 and 2017, 6,281 and 7,035 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 six month periods ended June 30, 2018 and 2017: RSUs DSUs Units Weighted Average Grant Date Fair Value Units Weighted Average Grant Date Fair Value Balance, January 1, 2018 12,919,846 $ 40.23 278,422 $ 37.46 Granted (including 636,207 RSUs relating to dividend participation) 3,974,389 $ 54.07 36,744 $ 52.18 Forfeited (105,853 ) $ 44.55 - - Vested (5,542,633 ) $ 42.86 - - Balance, June 30, 2018 11,245,749 $ 43.78 315,166 $ 39.18 Balance, January 1, 2017 11,698,138 $ 40.65 276,725 $ 36.05 Granted (including 739,079 RSUs relating to dividend participation) 5,134,126 $ 43.07 38,315 $ 44.30 Forfeited (92,011 ) $ 39.98 - - Vested (3,937,970 ) $ 45.36 (43,465 ) $ 35.77 Balance, June 30, 2017 12,802,283 $ 40.17 271,575 $ 37.26 In connection with RSUs that vested during the six month periods ended June 30, 2018 and 2017, the Company satisfied its minimum statutory tax withholding requirements in lieu of delivering 1,635,514 and 1,267,560 shares of Class A common stock during such respective six month periods. Accordingly, 3,907,119 and 2,670,410 shares of Class A common stock held by the Company were delivered during the six month periods ended June 30, 2018 and 2017, respectively. As of June 30, 2018, estimated unrecognized RSU compensation expense was approximately $203,205, with such expense expected to be recognized over a weighted average period of approximately 0.9 years subsequent to June 30, 2018. Restricted Stock The following is a summary of activity related to shares of restricted Class A common stock associated with compensation arrangements during the six month periods ended June 30, 2018 and 2017: Restricted Shares Weighted Average Grant Date Fair Value Balance, January 1, 2018 1,938,160 $ 40.54 Granted 529,987 $ 54.45 Forfeited (26,222 ) $ 47.00 Vested (848,187 ) $ 44.24 Balance, June 30, 2018 1,593,738 $ 43.09 Balance, January 1, 2017 1,655,073 $ 40.95 Granted 841,355 $ 42.58 Forfeited (32,568 ) $ 41.96 Vested (458,814 ) $ 45.57 Balance, June 30, 2017 2,005,046 $ 40.56 In connection with shares of restricted Class A common stock that vested during the six month periods ended June 30, 2018 and 2017, the Company satisfied its minimum statutory tax withholding requirements in lieu of delivering 289,831 and 135,528 shares of Class A common stock during such respective six month periods. Accordingly, 558,356 and 323,286 shares of Class A common stock held by the Company were delivered during the six month periods ended June 30, 2018 and 2017, respectively. The restricted stock awards include a cash dividend participation right equivalent to dividends paid on Class A common stock during the period, which will vest concurrently with the underlying restricted stock award. At June 30, 2018, estimated unrecognized restricted stock expense was approximately $31,084, with such expense to be recognized over a weighted average period of approximately 0.8 years subsequent to June 30, 2018. PRSUs PRSUs are RSUs that 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 Lazard Ltd’s performance over a three-year period. 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 generally can range from zero to two times the target number. PRSUs will vest on a single date approximately three years following the date of the grant, 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 Lazard Ltd 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 include dividend participation rights that provide that during vesting periods, the target number of PRSUs (or, following the relevant performance period, the actual number of shares of Class A common stock that are no longer subject to performance conditions) receive dividend equivalents at the same rate that dividends are paid on Class A common stock during such periods. These dividend equivalents are credited as RSUs that are not subject to the performance-based vesting criteria but are otherwise subject to the same restrictions as the underlying PRSUs to which they relate. The following is a summary of activity relating to PRSUs during the six month periods ended June 30, 2018 and 2017: PRSUs Weighted Average Grant Date Fair Value Balance, January 1, 2018 1,591,693 $ 42.46 Granted (a) 399,869 $ 56.80 Vested (799,402 ) $ 46.74 Balance, June 30, 2018 1,192,160 $ 44.39 Balance, January 1, 2017 1,590,756 $ 40.76 Granted (a) 458,113 $ 43.76 Vested (825,565 ) $ 42.27 Balance, June 30, 2017 1,223,304 $ 40.86 (a) Represents PRSU awards granted during the relevant year at the target payout level. In connection with certain PRSUs that vested or were settled during the six month periods ended June 30, 2018 and 2017, the Company satisfied its minimum statutory tax withholding requirements in lieu of delivering 91,962 and 126,264 shares of Class A common stock during such respective six month periods. Accordingly, 707,440 and 699,301 shares of Class A common stock held by the Company were delivered during the six month periods ended June 30, 2018 and 2017, respectively. 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. As of June 30, 2018, the total estimated unrecognized compensation expense was approximately $12,594, and the Company expects to amortize such expense over a weighted-average period of approximately 0.9 years subsequent to June 30, 2018. LFI and Other Similar Deferred Compensation Arrangements Commencing in February 2011, the Company granted LFI to eligible employees. In connection with LFI 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 condensed consolidated statement of operations. LFI 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 LFI and other similar deferred compensation arrangements during the six month periods ended June 30, 2018 and 2017: Prepaid Compensation Asset Compensation Liability Balance, January 1, 2018 $ 60,355 $ 182,301 Granted 104,551 104,551 Settled - (84,422 ) Forfeited (618 ) (876 ) Amortization (50,057 ) - Change in fair value related to: Decrease in fair value of underlying investments - (1,935 ) Adjustment for estimated forfeitures - 2,330 Other (1,424 ) (1,105 ) Balance, June 30, 2018 $ 112,807 $ 200,844 Prepaid Compensation Asset Compensation Liability Balance, January 1, 2017 $ 49,650 $ 170,388 Granted 77,580 77,580 Settled - (95,633 ) Forfeited (585 ) (933 ) Amortization (39,503 ) - Change in fair value related to: Increase in fair value of underlying investments - 13,106 Adjustment for estimated forfeitures - 2,138 Other 942 1,312 Balance, June 30, 2017 $ 88,084 $ 167,958 The amortization of the prepaid compensation asset will generally be recognized over a weighted average period of approximately 0.9 years subsequent to June 30, 2018. The following is a summary of the impact of LFI and other similar deferred compensation arrangements on “compensation and benefits” expense within the accompanying condensed consolidated statements of operations for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Amortization, net of forfeitures $ 36,293 $ 28,310 $ 52,129 $ 41,293 Change in the fair value of underlying investments (499 ) 5,753 (1,935 ) 13,106 Total $ 35,794 $ 34,063 $ 50,194 $ 54,399

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	14. 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”). The Company also offers defined contribution plans to its employees. The pension 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 for the service cost component, and “operating expenses — 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 following table summarizes the components of net periodic benefit cost (credit) related to the Company’s pension plans for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended June 30, 2018 2017 Components of Net Periodic Benefit Cost (Credit): Service cost $ 223 $ 335 Interest cost 3,977 4,086 Expected return on plan assets (7,583 ) (6,455 ) Amortization of: Prior service cost - - Net actuarial loss (gain) 1,245 1,552 Net periodic benefit cost (credit) $ (2,138 ) $ (482 ) Six Months Ended June 30, 2018 2017 Components of Net Periodic Benefit Cost (Credit): Service cost $ 453 $ 675 Interest cost 8,039 8,067 Expected return on plan assets (15,366 ) (12,560 ) Amortization of: Prior service cost - 30 Net actuarial loss (gain) 2,523 2,884 Net periodic benefit cost (credit) $ (4,351 ) $ (904 )

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	15. INCOME TAXES 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. Lazard Group, through its subsidiaries, is subject to state and local taxes on its income apportioned to various state and local jurisdictions. Outside the U.S., Lazard Group operates principally through subsidiary corporations that are subject to local income taxes in foreign jurisdictions. Lazard Group is also subject to New York City Unincorporated Business Tax (“UBT”) attributable to its operations apportioned to New York City. On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was enacted. The Tax Act significantly revises the U.S. corporate income tax system by, among other changes, lowering the corporate income tax rate from 35% to 21%, implementing a partial territorial tax system and imposing a one-time repatriation tax on the deemed repatriated earnings of foreign subsidiaries. The Tax Act also includes several provisions that may limit the benefit of the tax rate reduction, such as restricting the deductibility of interest expense and other corporate business expenses. The Tax Act further includes anti-base erosion provisions such as the base erosion and anti-abuse tax and tax on global intangible low-taxed income. As a result of the reduction of the U.S. federal corporate tax rate to 21%, the Company was required to remeasure its deferred tax assets and liabilities at the new federal income tax rate of 21% based on the balances that existed on the date of the enactment of the Tax Act. The impact of this remeasurement was immaterial to the Company. The Tax Act also requires companies to pay a one-time repatriation tax on previously unremitted earnings of certain non-U.S. corporate subsidiaries. Most of the Company’s operations outside the U.S. are conducted in “pass-through” entities for U.S. income tax purposes, and, as a result, the deemed repatriation transition tax does not apply to these pass-through entities or their earnings. The Company instead provides for U.S. income taxes on a current basis for the relevant portion of those earnings. The Company also conducts operations outside the U.S. through foreign corporate subsidiaries. The impact of the one-time repatriation tax was immaterial to the Company. In accordance with the guidance provided by Staff Accounting Bulletin No. 118, the Company has recognized the provisional tax impact related to the one-time deemed repatriation tax on certain foreign earnings and the remeasurement of our deferred tax assets. The impact of the Tax Act on the Company may differ from these provisional estimates, due to, among other items, the issuance of additional regulatory guidance, our interpretations of the provisions of the Tax Act, changes to certain estimates and amounts related to the earnings and profits of certain subsidiaries and the filing of our tax returns. We will recognize any changes to the provisional amounts as we refine our estimates and expect to complete our analysis of the provisional items during the second half of 2018. The Company recorded income tax provisions of $31,445 and $50,060 for the three month and six month periods ended June 30, 2018, respectively, and $32,440 and $54,435 for the three month and six month periods ended June 30, 2017, respectively, representing effective tax rates of 16.4%, 13.2%, 18.5% and 16.6%, respectively. The difference between the U.S. federal statutory rate of 21.0% and 35.0% for 2018 and 2017, respectively, 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) change in the valuation allowance affecting the provision for income taxes, (iii) taxes payable to foreign jurisdictions, (iv) excess net tax benefit for share-based incentive compensation, and (v) U.S. state and local taxes, which are incremental to the U.S. federal statutory tax rate. On January 1, 2017, the Company adopted new accounting guidance on share-based incentive compensation. As a result of the adoption of this new guidance, the Company recognized excess tax benefits of $14,085 and $2,018 from the vesting of share-based incentive compensation in the provision for income taxes in the condensed consolidated statements of operations for the six month periods ended June 30, 2018 and 2017, respectively. The Company also recorded deferred tax assets of $4,945, net of a valuation allowance of $12,090, as of January 1, 2017, for previously unrecognized excess tax benefits (including tax benefits from dividends or dividend equivalents) on share-based incentive compensation, with an offsetting adjustment to retained earnings.

Related Parties

Related Parties	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Parties	16. RELATED PARTIES Receivables from and Payables to Lazard Ltd Subsidiaries Lazard Group’s receivables from subsidiaries of Lazard Ltd at June 30, 2018 and December 31, 2017 included interest-bearing loans of $83,069 and $72, respectively, including accrued interest thereon. Interest income relating to interest-bearing loans with subsidiaries of Lazard Ltd amounted to $200 and $221 for the three month and six month periods ended June 30, 2018, respectively, and $10 and $143 for the three month and six month periods ended June 30, 2017, respectively. Lazard Group’s payables to subsidiaries of Lazard Ltd at June 30, 2018 and December 31, 2017 included interest-bearing loans, including interest thereon, of $62,036 and $64,203, respectively. Interest expense relating to interest-bearing loans with subsidiaries of Lazard Ltd amounted to $929 and $1,902 for the three month and six month periods ended June 30, 2018, respectively, and $931 and $1,875 for the three month and six month periods ended June 30, 2017, respectively. Sponsored Funds The Company serves as an investment advisor for certain affiliated investment companies and fund entities and receives management fees and, for the alternative investment funds, performance-based incentive fees for providing such services. Investment advisory fees relating to such services were $170,680 and $351,990 for the three month and six month periods ended June 30, 2018, respectively, and $167,382 and $307,959 for the three month and six month periods ended June 30, 2017, respectively, and are included in “asset management fees” on the condensed consolidated statements of operations. Of such amounts, $84,565 and $69,107 remained as receivables at June 30, 2018 and December 31, 2017, respectively, and are included in “fees receivable” on the condensed consolidated statements of financial condition. Other See Note 12 for information regarding related party transactions pertaining to shares repurchased from certain of our executive officers.

Regulatory Authorities

Regulatory Authorities	6 Months Ended
	Jun. 30, 2018
Regulatory Capital Requirements [Abstract]
Regulatory Authorities	17. 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 Certain U.K. subsidiaries of the Company, including LCL, Lazard Fund Managers Limited and Lazard Asset Management Limited (collectively, the “U.K. Subsidiaries”) are regulated by the Financial Conduct Authority. At June 30, 2018, the aggregate regulatory net capital of the U.K. Subsidiaries was $166,717, which exceeded the minimum requirement by $148,324. CFLF, under which asset management and commercial banking activities are carried out in France, is subject to regulation by the Autorité de Contrôle Prudentiel et de Résolution (“ACPR”) for its banking activities conducted through its subsidiary, LFB. LFB, as a registered bank, is engaged primarily in commercial and private banking services for clients and funds managed by LFG (asset management) and other clients, and asset-liability management. The investment services activities of the Paris group, exercised through LFB and other subsidiaries of CFLF, primarily LFG, also are subject to regulation and supervision by the Autorité des Marchés Financiers. At June 30, 2018, the consolidated regulatory net capital of CFLF was $130,702, which exceeded the minimum requirement set for regulatory capital levels by $76,071. In addition, 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 supervision, the combined European regulated group is required to comply with minimum requirements for regulatory net capital to be reported on a quarterly basis and satisfy periodic financial and other reporting obligations. At March 31, 2018, the regulatory net capital of the combined European regulated group was $176,098, which exceeded the minimum requirement set for regulatory capital levels by $63,607. Additionally, the combined European regulated group, together with our European Financial Advisory entities, is 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. 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 June 30, 2018, for those subsidiaries with regulatory capital requirements, their aggregate net capital was $158,343, which exceeded the minimum required capital by $130,629. At June 30, 2018, each of these subsidiaries individually was in compliance with its regulatory capital requirements. Any new or expanded 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	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Information	18. 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 its Financial Advisory and Asset Management business segments as described in Note 1. In addition, as described in Note 1, the Company records selected other activities in its Corporate segment. The Company’s segment information for the three month and six month periods ended June 30, 2018 and 2017 is 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, human resources, 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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 Financial Advisory Net Revenue $ 419,468 $ 410,632 $ 827,935 $ 746,316 Operating Expenses 324,287 311,285 646,795 570,647 Operating Income $ 95,181 $ 99,347 $ 181,140 $ 175,669 Asset Management Net Revenue $ 352,588 $ 309,878 $ 706,871 $ 593,241 Operating Expenses 229,561 215,901 459,230 404,652 Operating Income $ 123,027 $ 93,977 $ 247,641 $ 188,589 Corporate Net Revenue $ (17,417 ) $ (4,484 ) $ (26,906 ) $ (1,054 ) Operating Expenses 8,977 13,594 23,109 34,946 Operating Loss $ (26,394 ) $ (18,078 ) $ (50,015 ) $ (36,000 ) Total Net Revenue $ 754,639 $ 716,026 $ 1,507,900 $ 1,338,503 Operating Expenses 562,825 540,780 1,129,134 1,010,245 Operating Income $ 191,814 $ 175,246 $ 378,766 $ 328,258 As Of June 30, 2018 December 31, 2017 Total Assets Financial Advisory $ 855,321 $ 817,185 Asset Management 709,833 756,398 Corporate 2,505,465 2,726,990 Total $ 4,070,619 $ 4,300,573

Organization and Basis of Pre28

Organization and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	Organization The accompanying condensed consolidated financial statements are those of Lazard Group LLC and its subsidiaries (collectively referred to as “Lazard Group” or the “Company”). Lazard Group is a Delaware limited liability company and is governed by an Amended and Restated Operating Agreement dated as of October 26, 2015, as amended (the “Operating Agreement”). Lazard Ltd, a Bermuda holding company, and its subsidiaries (collectively referred to as “Lazard Ltd”), including its indirect investment in 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 100% of all outstanding Lazard Group common membership interests as of June 30, 2018 and December 31, 2017. Lazard Ltd, through its control of the managing members of Lazard Group, controls Lazard Group. Lazard Group’s 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”), capital advisory, capital raising, restructurings, shareholder advisory, sovereign advisory and other strategic advisory, and • Asset Management, which offers a broad range of global investment solutions and investment management services in equity and fixed income strategies, asset allocation 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, deferred tax assets, outstanding indebtedness, certain contingent obligations, and assets and liabilities associated with Lazard Group’s Paris-based subsidiary Lazard Frères Banque SA (“LFB”).
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of Lazard Group 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 Group’s Annual Report on Form 10-K for the year ended December 31, 2017. The accompanying December 31, 2017 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. For example, 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 six month periods ended June 30, 2018 are not indicative of the results to be expected for any future interim or annual period. The condensed consolidated financial statements include 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 Lazard Frères Gestion SAS (“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 entities in which it has a controlling financial interest. The Company consolidates: • Voting interest entities (“VOEs”) where the Company holds a majority of the voting interest in such VOEs, and • Variable interest entities (“VIEs”) where the Company is the primary beneficiary having the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses of, or receive benefits from, the VIE that could be potentially significant to the VIE. 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 either (i) applies the equity method of accounting in which it records a proportionate share of the entity’s net earnings, or (ii) elects the option to measure at fair value. Intercompany transactions and balances have been eliminated. Certain prior period amounts have been reclassified to conform to the current period presentation, specifically related to the adoption of new guidance impacting the condensed consolidated statements of cash flows (see Note 2).
Recent Accounting Developments	Revenue from Contracts with Customers— In May 2014, the FASB issued comprehensive new revenue recognition guidance. The guidance requires a company to recognize revenue when it transfers promised services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those services and requires enhanced disclosures. The guidance also changes the accounting for certain contract costs, including whether they may be offset against revenue in the condensed consolidated statements of operations. On July 9, 2015, the FASB approved the deferral of the effective date of the new revenue guidance by one year to annual reporting periods beginning after December 15, 2017. The guidance may be adopted using a full retrospective approach or a modified cumulative effect approach. The Company adopted the revenue recognition guidance upon its effective date of January 1, 2018 using the modified cumulative effect approach. The Company applied the new guidance to contracts that have not yet been completed as of the adoption date. The Company’s adoption efforts included the identification of revenue within the scope of the guidance and the evaluation of revenue contracts. The Company evaluated the potential impact of the new guidance, including (i) the timing of revenue recognition for Financial Advisory and Asset Management fees and (ii) the presentation of certain contract costs. With respect to revenue recognition, the Company assessed the impact of the new guidance on the recognition of fees for Financial Advisory (e.g., transaction completion, transaction announcement and retainers), and Asset Management (e.g., management and incentive fees). This assessment included an analysis of whether the Company’s fulfillment of its performance obligations would be deemed to occur over time, or at specific points in time, under the new guidance. Specifically, recognition would be deemed to occur over time if the client receives and consumes benefits from the services as the Company performs the services. The Company concluded that Financial Advisory and Asset Management fees would typically be recognized over time as performance occurs, subject to constraints, using an appropriate measure of progress based on resources consumed, which is consistent with when the client receives benefits. There was no material impact to the Company’s recognition of revenue upon adoption of the new guidance. The new guidance requires the Company to prospectively present certain contract costs on a gross basis. The most significant changes with respect to presentation relate to (a) certain distribution costs within our Asset Management business and (b) certain reimbursable deal costs within our Financial Advisory business, both of which were previously presented net against revenues and are now presented as expenses on a gross basis under the new guidance because the Company is primarily responsible for fulfilling the promise of the arrangement. For the three month and six month periods ended June 30, 2018, the presentation of such costs on a gross basis resulted in an increase to net revenue of $24,053 and $47,609, respectively, primarily comprised of increases to asset management fees and investment banking and other advisory fees. In addition, there was a corresponding increase to operating expenses of $24,053 and $47,609, respectively, primarily comprised of an increase to distribution costs presented within fund administration and outsourced services and an increase to reimbursable deal costs presented within marketing and business development. These amounts would have been presented on a net basis prior to the adoption of the new guidance, and there was no material impact to net income as a result of the gross basis of presentation under the new guidance. See Note 3 for further information on contracts within the scope of the new guidance. Classification of Certain Cash Receipts and Cash Payments— In August and November 2016, the FASB issued updated guidance which clarifies how a company should classify certain cash receipts and cash payments on the statement of cash flows and clarifies that restricted cash should be included in the total of cash and cash equivalents on the statement of cash flows. The new guidance for both updates is effective for annual and interim periods beginning after December 15, 2017 and is to be applied on a retrospective basis. The Company adopted this new guidance on January 1, 2018. The adoption of the new guidance in the first quarter of 2018 resulted in the reclassification of “cash deposited with clearing organization and other segregated cash” and “deposits with banks and short-term investments” from operating activities to components of “cash and cash equivalents and restricted cash” on the condensed consolidated statement of cash flows. In addition, the Company reclassified cash flows related to customer deposits from operating activities to financing activities. This resulted in changes in deposits with banks and short-term investments and customer deposits no longer being reflected in cash flows from operating activities. Except for the reclassification of these items on the condensed consolidated statement of cash flows, the new guidance had no impact on the Company’s financial statements. Clarifying the Definition of a Business— In January 2017, the FASB issued updated guidance to clarify the definition of a business within the context of business combinations. The updated guidance requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, such asset or group of assets is not a business. This updated guidance is expected to reduce the number of transactions that need to be further evaluated as business combinations. If further evaluation is necessary, the updated guidance will require that a business set include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output. The updated guidance will remove the evaluation of whether a market participant could replace missing elements. The new guidance is effective for annual and interim periods beginning after December 15, 2017 and is to be applied on a prospective basis. The Company adopted the new guidance on January 1, 2018 and it will be applied to business combinations on a prospective basis. Compensation — — — I n March 2016, the FASB issued updated guidance on the presentation of net benefit cost in the statement of operations and the components eligible for capitalization. The new guidance requires that only the service cost component of net periodic pension cost and net periodic postretirement benefit cost be presented with other employee compensation costs in operating expenses, applied on a retrospective basis. The other components of net benefit cost, including amortization of prior service cost, and gains and losses from settlements and curtailments, are included in other operating expenses. The new guidance also stipulates that only the service cost component of net benefit cost is eligible for capitalization, applied on a prospective basis. This new guidance is effective for annual and interim periods beginning after December 15, 2017. The Company adopted the new guidance on January 1, 2018 and there was no material impact to the Company’s financial statements. Compensation—Stock Compensation: Scope of Modification Accounting— In May 2017, the FASB issued updated guidance on modifications to share-based payment awards. The updated guidance requires entities to account for the effects of a modification to a share-based payment award unless the following are all the same immediately before and after the modification: (i) the fair value of the award, (ii) the vesting conditions of the award, and (iii) the classification of the award as an equity instrument or a liability instrument. This new guidance is effective for annual and interim periods beginning after December 15, 2017 and is to be applied on a prospective basis. The Company adopted the new guidance on January 1, 2018, and there was no material impact to the Company’s financial statements. Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income— In February 2018, the FASB issued updated guidance on the tax effects of items in “accumulated other comprehensive income (loss), net of tax” (“AOCI”). Specifically, the new guidance will permit, but not require, a reclassification from AOCI to retained earnings for stranded tax effects resulting from the newly enacted federal corporate income tax rate under the Tax Cuts and Jobs Act of 2017 (see Note 15). The amount of the reclassification would be the difference between the historical corporate income tax rate and the newly enacted 21% corporate income tax rate. The new guidance is effective for annual and interim periods beginning after December 15, 2018, with an option to apply it in the period of adoption or on a retrospective basis for each period in which the effect of the change in the U.S. federal corporate income tax rate is recognized. Early adoption of the new guidance is permitted for public business entities for reporting periods for which financial statements have not yet been issued. The Company is currently evaluating the new guidance. Leases —In February 2016, the FASB issued updated guidance for leases. The guidance requires a lessee to (i) recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in the statement of financial condition, (ii) recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term on a generally straight-line basis, and (iii) classify all cash payments within operating activities in the statement of cash flows. The new guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. The new guidance is to be applied on a modified retrospective basis. The Company is currently evaluating the new guidance. Improvements to Nonemployee Share-Based Payment Accounting— In June 2018, the FASB issued updated guidance to simplify the accounting for nonemployee share-based payment transactions. The new guidance generally requires equity-classified nonemployee share-based payment awards to be measured at the grant date, which is the date at which a grantor and grantee reach a mutual understanding of the key terms and conditions of a share-based payment award. This update generally aligns the accounting for equity-classified share-based payment awards to nonemployees with the measurement date required for employees. The new guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. Upon adoption, the new guidance would be applied on a modified retrospective basis. The Company is currently evaluating the new guidance. Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments —In June 2016, the FASB issued new guidance regarding the measurement of credit losses on financial instruments. The new guidance replaces the incurred loss impairment methodology in the current guidance with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. The new guidance is effective for annual and interim periods beginning after December 15, 2019 with early adoption permitted for fiscal years beginning after December 15, 2018. The Company is currently evaluating the new guidance. Intangibles—Goodwill and Other: Simplifying the Test for Goodwill Impairment —In January 2017, the FASB issued updated guidance which eliminated Step 2 from the goodwill impairment test. Step 2 is the process of measuring a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The new guidance requires entities to measure a goodwill impairment loss as the amount by which a reporting unit’s carrying value exceeds its fair value, limited to the carrying amount of goodwill. The FASB also eliminated the requirements for entities that have reporting units with zero or negative carrying amounts to perform a qualitative assessment for the goodwill impairment test. Instead, those entities would be required to disclose the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount. The new guidance is effective for interim or annual goodwill impairment tests performed in fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the new guidance.
Revenue Recognition Policy	Investment Banking and Other Advisory —Fees for Financial Advisory services are recorded when: (i) a contract with a client has been identified, (ii) the performance obligations in the contract have been identified, (iii) the fee or other transaction price has been determined; (iv) the fee or other transaction price has been allocated to each performance obligation in the contract; and (v) the Company has satisfied the applicable performance obligation. The expenses that are directly related to such transactions are recorded as incurred and presented within operating expenses when the Company is primarily responsible for fulfilling the promise of the arrangement. Revenues associated with the reimbursement of such expenses are recorded when the Company is contractually entitled to reimbursement and presented within investment banking and other advisory fees. Asset Management Fees —Fees for Asset Management services are primarily comprised of management fees and incentive fees. Management fees are derived from fees for investment management and other services provided to clients. Revenue is recorded in accordance with the same five criteria as Financial Advisory fees, which generally results in management fees being recorded on a daily, monthly or quarterly basis, primarily based on a percentage of client assets managed. Fees vary with the type of assets managed, with higher fees earned on equity assets, alternative investment (such as hedge fund) and private equity funds, and lower fees earned on fixed income and money market products. Expenses that are directly related to the sale or distribution of fund interests are recorded as incurred and presented within operating expenses when the Company is primarily responsible for fulfilling the promise of the arrangement. Revenues associated with the reimbursement of such expenses are recorded when the Company is contractually entitled to reimbursement and presented within asset management fees. In addition, the Company earns performance-based incentive fees on various investment products, including traditional products and alternative investment funds such as hedge funds and private equity funds. For hedge funds, incentive fees are calculated based on a specific percentage of a fund’s net appreciation, in some cases in excess of established benchmarks or thresholds. The Company records incentive fees on traditional products and hedge funds when a significant reversal in the amount of the cumulative revenue to be recognized is not probable, which is typically at the end of the relevant performance measurement period. The incentive fee measurement period is generally an annual period (unless an account is terminated during the year). The incentive fees received at the end of the measurement period are not subject to reversal or payback. Incentive fees on hedge funds generally are subject to loss carryforward provisions in which losses incurred by the hedge funds in any year are applied against certain gains realized by the hedge funds in future periods before any incentive fees can be earned. For private equity funds, incentive fees may be earned in the form of a “carried interest” if profits arising from realized investments exceed a specified threshold. Typically, such carried interest is ultimately calculated on a whole-fund basis and, therefore, clawback of carried interests during the life of the fund can occur. As a result, the Company records incentive fees earned on our private equity funds when a significant reversal in the amount of the cumulative revenue to be recognized is not probable, which is typically at the end of the relevant performance period. Receivables relating to asset management and incentive fees are reported in “fees receivable” on the consolidated statements of financial condition.
Derivative Instruments	The Company enters into forward foreign currency exchange rate contracts, interest rate swaps, interest rate futures, total return swap contracts on various equity and debt indices and other derivative contracts to economically 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 condensed consolidated statements of financial condition. Gains and losses on the Company’s derivative instruments are generally included in “interest income” and “interest expense”, respectively, or “revenue-other”, depending on the nature of the underlying item, in the condensed consolidated statements of operations. In addition to the derivative instruments described above, the Company records derivative liabilities relating to its obligations pertaining to LFI 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 condensed consolidated statements of financial condition. Changes in the fair value of the derivative liabilities are included in “compensation and benefits” in the condensed 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 LFI and other similar deferred compensation arrangements, which are reported in “revenue-other” in the condensed consolidated statements of operations.
Fair Value Measurement Policy	Fair Value Hierarchy of Investments and Certain Other Assets and Liabilities —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, or (ii) 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. 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, debt funds and equity funds is classified as Level 1 when the fair values are primarily based on the publicly reported closing price for the fund. The fair value of securities sold, not yet purchased, is classified as Level 1 when the fair values are based on unadjusted quoted prices in active markets. The fair value of the contingent consideration liability is classified as Level 3 and the fair value of the liability is remeasured at each reporting period. The inputs used to derive the fair value of the contingent consideration include the application of probabilities when assessing certain performance thresholds for the relevant periods. The fair value of derivatives entered into by the Company is classified as Level 2 and is 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 total return swaps is based on the change in fair value 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 LFI and other similar deferred compensation arrangements is based on the value of the underlying investments, adjusted for forfeitures. See Note 7. Investments Measured at Net Asset Value (“NAV”) —As a practical expedient, the Company uses NAV or its equivalent to measure the fair value of certain investments. NAV is primarily determined based on information provided by external fund administrators. The Company’s investments valued at NAV as a practical expedient in (i) alternative investment funds, debt funds and equity funds are redeemable in the near term, and (ii) private equity funds are not redeemable in the near term as a result of redemption restrictions.
Employer Contributions to Pension Plans	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.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue Recognition [Abstract]
Revenue Based on Business Segment Results	The Company disaggregates revenue based on its business segment results and believes that the following information provides a reasonable representation of how performance obligations relate to the nature, amount, timing and uncertainty of revenue and cash flows: Three Months Ended Six Months Ended June 30, 2018 (d) June 30, 2018 (d) Net Revenue: Financial Advisory (a) $ 419,468 $ 827,935 Asset Management: Management Fees and Other (b) $ 340,160 $ 688,844 Incentive Fees (c) 12,428 18,027 Total Asset Management $ 352,588 $ 706,871

Receivables (Tables)

Receivables (Tables)	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Schedule of Activity in Allowance for Doubtful Accounts	Activity in the allowance for doubtful accounts for the three month and six month periods ended June 30, 2018 and 2017 was as follows: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Beginning Balance $ 38,505 $ 29,662 $ 23,692 $ 16,386 Bad debt expense, net of recoveries 666 180 16,618 13,831 Charge-offs, foreign currency translation and other adjustments (4,265 ) (4,748 ) (5,404 ) (5,123 ) Ending Balance $ 34,906 $ 25,094 $ 34,906 $ 25,094

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments Schedule [Abstract]
Company's Investments and Securities Sold, Not Yet Purchased	The Company’s investments and securities sold, not yet purchased, consist of the following at June 30, 2018 and December 31, 2017: June 30, December 31, 2018 2017 Interest-bearing deposits $ 530 $ 556 Debt 74,583 6 Equities 39,818 45,257 Funds: Alternative investments (a) 26,097 20,993 Debt (a) 87,529 84,077 Equity (a) 209,379 199,618 Private equity 67,258 76,679 390,263 381,367 Total investments 505,194 427,186 Less: Interest-bearing deposits 530 556 Investments, at fair value $ 504,664 $ 426,630 Securities sold, not yet purchased, at fair value (included in “other liabilities”) $ 4,419 $ 7,338 (a) Interests in alternative investment funds, debt funds and equity funds include investments with fair values of $11,898, $57,444 and $147,862, respectively, at June 30, 2018 and $11,213, $48,391 and $131,893, respectively, at December 31, 2017, held in order to satisfy the Company’s liability upon vesting of previously granted Lazard Fund Interests (“LFI”) and other similar deferred compensation arrangements. LFI represent grants by the Company to eligible employees of actual or notional interests in a number of Lazard-managed funds, subject to service-based vesting conditions (see Notes 7 and 13).
Schedule of Trading Securities Net Unrealized Investment Gains and Losses	During the three month and six month periods ended June 30, 2018 and 2017, the Company reported in “revenue-other” on its condensed consolidated statements of operations net unrealized investment gains and losses pertaining to “trading” securities still held as of the reporting date as follows: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Net unrealized investment gains (losses) $ (5,864 ) $ 7,803 $ (15,155 ) $ 20,983

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Classification of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis and Investments Measured at NAV	The following tables present, as of June 30, 2018 and December 31, 2017, the classification of (i) investments and certain other assets and liabilities measured at fair value on a recurring basis within the fair value hierarchy and (ii) investments measured at NAV or its equivalent as a practical expedient: June 30, 2018 Level 1 Level 2 Level 3 NAV Total Assets: Investments: Debt $ 74,583 $ - $ - $ - $ 74,583 Equities 38,189 - 1,629 - 39,818 Funds: Alternative investments 25,168 - - 929 26,097 Debt 87,522 - - 7 87,529 Equity 209,326 - - 53 209,379 Private equity - - - 67,258 67,258 Derivatives - 6,399 - - 6,399 Total $ 434,788 $ 6,399 $ 1,629 $ 68,247 $ 511,063 Liabilities: Securities sold, not yet purchased $ 4,419 $ - $ - $ - $ 4,419 Contingent consideration liability 3,470 - 3,470 Derivatives - 202,975 - - 202,975 Total $ 4,419 $ 202,975 $ 3,470 $ - $ 210,864 December 31, 2017 Level 1 Level 2 Level 3 NAV Total Assets: Investments: Debt $ 6 $ - $ - $ - $ 6 Equities 43,665 - 1,592 - 45,257 Funds: Alternative investments 17,353 - - 3,640 20,993 Debt 84,071 - - 6 84,077 Equity 199,565 - - 53 199,618 Private equity - - - 76,679 76,679 Derivatives - 3,732 - - 3,732 Total $ 344,660 $ 3,732 $ 1,592 $ 80,378 $ 430,362 Liabilities: Securities sold, not yet purchased $ 7,338 $ - $ - $ - $ 7,338 Contingent consideration liability - - 4,656 - 4,656 Derivatives - 198,417 - - 198,417 Total $ 7,338 $ 198,417 $ 4,656 $ - $ 210,411
Summary of Changes in Fair Value of Company's Level 3 Assets and Liabilities	The following tables provide a summary of changes in fair value of the Company’s Level 3 assets and liabilities for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended June 30, 2018 Beginning Balance Net Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,599 $ 62 $ - $ - $ (32 ) $ 1,629 Total Level 3 Assets $ 1,599 $ 62 $ - $ - $ (32 ) $ 1,629 Liabilities: Contingent consideration liability $ 4,661 $ (1,191 ) $ - $ - $ - $ 3,470 Total Level 3 Liabilities $ 4,661 $ (1,191 ) $ - $ - $ - $ 3,470 Six Months Ended June 30, 2018 Beginning Balance Net Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,592 $ 61 $ 1 $ - $ (25 ) $ 1,629 Total Level 3 Assets $ 1,592 $ 61 $ 1 $ - $ (25 ) $ 1,629 Liabilities: Contingent consideration liability $ 4,656 $ (1,186 ) $ - $ - $ - $ 3,470 Total Level 3 Liabilities $ 4,656 $ (1,186 ) $ - $ - $ - $ 3,470 Three Months Ended June 30, 2017 Beginning Balance Net Unrealized/ Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,537 $ (128 ) $ 1,661 $ - $ 2 $ 3,072 Total Level 3 Assets $ 1,537 $ (128 ) $ 1,661 $ - $ 2 $ 3,072 Liabilities: Contingent consideration liability $ 4,078 $ 30 $ - $ - $ - $ 4,108 Total Level 3 Liabilities $ 4,078 $ 30 $ - $ - $ - $ 4,108 Six Months Ended June 30, 2017 Beginning Balance Net Realized Gains/Losses Included In Earnings (a) Purchases/ Acquisitions Sales/ Dispositions Foreign Currency Translation Adjustments Ending Balance Assets: Investments: Equities $ 1,508 $ (126 ) $ 1,661 $ (8 ) $ 37 $ 3,072 Total Level 3 Assets $ 1,508 $ (126 ) $ 1,661 $ (8 ) $ 37 $ 3,072 Liabilities: Contingent consideration liability $ 3,364 $ 744 $ - $ - $ - $ 4,108 Total Level 3 Liabilities $ 3,364 $ 744 $ - $ - $ - $ 4,108 (a) Earnings recorded in “other revenue” for investments in equities for the three month and six month periods ended June 30, 2018 and the three month and six month periods ended June 30, 2017 include net unrealized gains (losses) of $62, $61, $(128) and $(128), respectively. Earnings recorded in “amortization and other acquisition-related (benefits) costs” for the contingent consideration liability for the three month and six month periods ended June 30, 2018 and the three month and six month periods ended June 30, 2017 include unrealized (gains) losses of $(1,191), $(1,186), $30 and $744, respectively.
Fair Value of Certain Investments Based on NAV	The following tables present, at June 30, 2018 and December 31, 2017, certain investments that are valued using NAV or its equivalent as a practical expedient in determining fair value: June 30, 2018 Estimated Liquidation Period of Investments Not Redeemable Investments Redeemable Fair Value Unfunded Commitments % of Fair Value Not Redeemable % Next 5 Years % 5-10 Years % Thereafter Redemption Frequency Redemption Notice Period Alternative Hedge funds $ 332 $ - NA NA NA NA (a) 60 days Funds of funds 25 - NA NA NA NA (b) 90 days Other 572 - NA NA NA NA (c) <30-60 days Debt funds 7 - NA NA NA NA (d) 30 days Equity funds 53 - NA NA NA NA (e) <30-90 days Private equity funds: Equity growth 67,258 8,650 (f) 100 % 18 % 39 % 43 % NA NA Total $ 68,247 $ 8,650 (a) monthly (100%) (b) quarterly (100%) (c) daily (6%) and monthly (94%) (d) daily (100%) (e) daily (19%), monthly (49%) and quarterly (32%) (f) Unfunded commitments to private equity investments consolidated but not owned by Lazard of $15,517 are excluded. Such commitments are required to be funded by capital contributions from noncontrolling interest holders. December 31, 2017 Estimated Liquidation Period of Investments Not Redeemable Investments Redeemable Fair Value Unfunded Commitments % of Fair Value Not Redeemable % Next 5 Years % 5-10 Years % Thereafter Redemption Frequency Redemption Notice Period Alternative Hedge funds $ 2,517 $ - NA NA NA NA (a) <30-60 days Funds of funds 528 - NA NA NA NA (b) <30-90 days Other 595 - NA NA NA NA (c) <30-60 days Debt funds 6 - NA NA NA NA (d) 30 days Equity funds 53 - NA NA NA NA (e) <30-90 days Private equity funds: Equity growth 76,679 10,300 (f) 100 % 16 % 38 % 46 % NA NA Total $ 80,378 $ 10,300 (a) weekly (3%), monthly (5%) and quarterly (92%) (b) monthly (97%) and quarterly (3%) (c) daily (6%) and monthly (94%) (d) daily (100%) (e) daily (18%), monthly (50%) and quarterly (32%) (f) Unfunded commitments to private equity investments consolidated but not owned by Lazard of $5,902 are excluded. Such commitments are required to be funded by capital contributions from noncontrolling interest holders.

Derivatives (Tables)

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Fair Values of Derivatives Reported on Condensed Consolidated Statements of Financial Condition	The table below presents the fair value of the Company’s derivative instruments reported within “other assets” and “other liabilities” and the fair value of the Company’s derivative liabilities relating to its obligations pertaining to LFI and other similar deferred compensation arrangements reported within “accrued compensation and benefits” (see Note 13) on the accompanying condensed consolidated statements of financial condition as of June 30, 2018 and December 31, 2017: June 30, December 31, 2018 2017 Derivative Assets: Forward foreign currency exchange rate contracts $ 1,193 $ 3,314 Total return swaps and other (a) 5,206 418 $ 6,399 $ 3,732 Derivative Liabilities: Forward foreign currency exchange rate contracts $ 2,122 $ 4,846 Total return swaps and other (a) 9 11,270 LFI and other similar deferred compensation arrangements 200,844 182,301 $ 202,975 $ 198,417 (a) For total return swaps, amounts represent the netting of gross derivative assets and liabilities of $5,789 and $592 as of June 30, 2018, respectively, and $469 and $11,321 as of December 31, 2017, 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 $1,216 and $17,616 as of June 30, 2018 and December 31, 2017, 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 LFI 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 six month periods ended June 30, 2018 and 2017, were as follows: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Forward foreign currency exchange rate contracts $ 6,236 $ (6,630 ) $ 3,753 $ (5,158 ) LFI and other similar deferred compensation arrangements 499 (5,753 ) 1,935 (13,106 ) Total return swaps and other 790 (3,597 ) 2,446 (8,982 ) Total $ 7,525 $ (15,980 ) $ 8,134 $ (27,246 )

Property (Tables)

Property (Tables)	6 Months Ended
	Jun. 30, 2018
Property Plant And Equipment [Abstract]
Components of Property	At June 30, 2018 and December 31, 2017, property consisted of the following: Estimated Depreciable June 30, December 31, Life in Years 2018 2017 Buildings 33 $ 147,669 $ 151,912 Leasehold improvements 3-20 185,680 173,102 Furniture and equipment 3-10 192,752 183,510 Construction in progress 13,497 13,120 Total 539,598 521,644 Less - Accumulated depreciation and amortization 324,863 317,816 Property $ 214,735 $ 203,828

Goodwill and Other Intangible35

Goodwill and Other Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Components of Goodwill and Other Intangible Assets	The components of goodwill and other intangible assets at June 30, 2018 and December 31, 2017 are presented below: June 30, December 31, 2018 2017 Goodwill $ 355,933 $ 362,760 Other intangible assets (net of accumulated amortization) 4,754 5,274 $ 360,687 $ 368,034
Changes in Carrying Amount of Goodwill	Changes in the carrying amount of goodwill for the six month periods ended June 30, 2018 and 2017 are as follows: Six Months Ended June 30, 2018 2017 Balance, January 1 $ 362,760 $ 352,124 Foreign currency translation adjustments (6,827 ) 7,968 Balance, June 30 $ 355,933 $ 360,092
Gross Cost and Accumulated Amortization of Other Intangible Assets	The gross cost and accumulated amortization of other intangible assets as of June 30, 2018 and December 31, 2017, by major intangible asset category, are as follows: June 30, 2018 December 31, 2017 Gross Cost Accumulated Amortization Net Carrying Amount Gross Cost Accumulated Amortization Net Carrying Amount Success/incentive fees $ 33,040 $ 29,060 $ 3,980 $ 33,040 $ 27,927 $ 5,113 Management fees, customer relationships and non-compete agreements 34,186 33,412 774 33,436 33,275 161 $ 67,226 $ 62,472 $ 4,754 $ 66,476 $ 61,202 $ 5,274
Estimated Future Amortization Expense	Estimated future amortization expense is as follows: Year Ending December 31, Amortization Expense (a) 2018 (July 1 through December 31) $ 1,120 2019 1,648 2020 1,648 2021 150 2022 150 2023 38 Total amortization expense $ 4,754 (a) Approximately 37% of intangible asset amortization is attributable to a noncontrolling interest.

Senior Debt (Tables)

Senior Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Senior Debt	Senior debt is comprised of the following as of June 30, 2018 and December 31, 2017: Outstanding as of Initial Annual June 30, 2018 December 31, 2017 Principal Amount Maturity Date Interest Rate(a) Principal Unamortized Debt Costs Carrying Value Principal Unamortized Debt Costs Carrying Value Lazard Group 2020 Senior Notes $ 500,000 11/14/20 4.25 % $ 500,000 $ 2,187 $ 497,813 $ 500,000 $ 2,647 $ 497,353 Lazard Group 2025 Senior Notes 400,000 2/13/25 3.75 % 400,000 3,124 396,876 400,000 3,361 396,639 Lazard Group 2027 Senior Notes 300,000 3/1/27 3.625 % 300,000 3,412 296,588 300,000 3,609 296,391 Total $ 1,200,000 $ 8,723 $ 1,191,277 $ 1,200,000 $ 9,617 $ 1,190,383 (a) The effective interest rates of Lazard Group’s 4.25% senior notes due November 14, 2020 (the “2020 Notes”), Lazard Group’s 3.75% senior notes due February 13, 2025 (the “2025 Notes”) and Lazard Group’s 3.625% senior notes due March 1, 2027 (the “2027 Notes”) are 4.43%, 3.87% and 3.76%, respectively.

Members' Equity (Tables)

Members' Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Share Repurchase Authorized by Board of Directors	Share Repurchase Program — During the six month period ended June 30, 2018 and since 2015, the Board of Directors of Lazard authorized the repurchase of Lazard Ltd Class A common stock as set forth in the table below: Date Repurchase Authorization Expiration February 2015 $ 150,000 December January 2016 $ 200,000 December April 2016 $ 113,182 December November 2016 $ 236,000 December October 2017 $ 200,000 December April 2018 $ 300,000 December 31, 2020
Schedule of Share Repurchase Program	The Company expects that the share repurchase program will primarily be used to offset a portion of the shares that have been or will be issued under the Lazard Ltd 2008 Incentive Compensation Plan (the “2008 Plan”) and the Lazard Ltd 2018 Incentive Compensation Plan (the “2018 Plan”). Pursuant to the share repurchase program, purchases have been made in the open market or through privately negotiated transactions. The rate at which the Company purchases shares in connection with the share repurchase program may vary from quarter to quarter due to a variety of factors. Purchases with respect to such program are set forth in the table below: Six Months Ended June 30: Number of Shares Purchased Average Price Per Share 2017 4,268,479 $ 43.32 2018 4,147,526 $ 53.96
Accumulated Other Comprehensive Income (Loss), Net of Tax	Accumulated Other Comprehensive Income (Loss), Net of Tax — The tables below reflect the balances of each component of AOCI at June 30, 2018 and 2017 and activity during the three month and six month periods then ended: Three Months Ended June 30, 2018 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, April 1, 2018 $ (24,841 ) $ (155,418 ) $ (180,259 ) $ - $ (180,259 ) Activity: Other comprehensive income (loss) before reclassifications (40,576 ) 8,300 (32,276 ) (1 ) (32,275 ) Adjustments for items reclassified to earnings, net of tax - 777 777 - 777 Net other comprehensive income (loss) (40,576 ) 9,077 (31,499 ) (1 ) (31,498 ) Balance, June 30, 2018 $ (65,417 ) $ (146,341 ) $ (211,758 ) $ (1 ) $ (211,757 ) Six Months Ended June 30, 2018 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, January 1, 2018 $ (43,790 ) $ (151,466 ) $ (195,256 ) $ - $ (195,256 ) Activity: Other comprehensive income (loss) before reclassifications (21,627 ) 3,286 (18,341 ) (1 ) (18,340 ) Adjustments for items reclassified to earnings, net of tax - 1,839 1,839 - 1,839 Net other comprehensive income (loss) (21,627 ) 5,125 (16,502 ) (1 ) (16,501 ) Balance, June 30, 2018 $ (65,417 ) $ (146,341 ) $ (211,758 ) $ (1 ) $ (211,757 ) Three Months Ended June 30, 2017 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, April 1, 2017 $ (96,007 ) $ (160,880 ) $ (256,887 ) $ (2 ) $ (256,885 ) Activity: Other comprehensive income (loss) before reclassifications 25,323 (8,609 ) 16,714 1 16,713 Adjustments for items reclassified to earnings, net of tax - 1,356 1,356 - 1,356 Net other comprehensive income (loss) 25,323 (7,253 ) 18,070 1 18,069 Balance, June 30, 2017 $ (70,684 ) $ (168,133 ) $ (238,817 ) $ (1 ) $ (238,816 ) Six Months Ended June 30, 2017 Currency Translation Adjustments Employee Benefit Plans Total AOCI Amount Attributable to Noncontrolling Interests Total Lazard Group AOCI Balance, January 1, 2017 $ (109,306 ) $ (161,471 ) $ (270,777 ) $ (2 ) $ (270,775 ) Activity: Other comprehensive income (loss) before reclassifications 38,622 (9,104 ) 29,518 1 29,517 Adjustments for items reclassified to earnings, net of tax - 2,442 2,442 - 2,442 Net other comprehensive income (loss) 38,622 (6,662 ) 31,960 1 31,959 Balance, June 30, 2017 $ (70,684 ) $ (168,133 ) $ (238,817 ) $ (1 ) $ (238,816 )
Adjustments for Items Reclassified Out of AOCI	The table below reflects adjustments for items reclassified out of AOCI, by component, for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Amortization relating to employee benefit plans (a) $ 1,245 $ 1,552 $ 2,523 $ 2,914 Less - related income taxes 468 196 684 472 Total reclassifications, net of tax $ 777 $ 1,356 $ 1,839 $ 2,442 ( a ) Included in the computation of net periodic benefit cost (see Note 14). Such amounts are included in “operating expenses —
Net Income Attributable to Noncontrolling Interests	The tables below summarize net income attributable to noncontrolling interests for the three month and six month periods ended June 30, 2018 and 2017 and noncontrolling interests as of June 30, 2018 and December 31, 2017 in the Company’s condensed consolidated financial statements: Net Income Attributable to Noncontrolling Interests Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Edgewater $ 1,415 $ 520 $ 3,383 $ 3,397 Other 1 2 2 2 Total $ 1,416 $ 522 $ 3,385 $ 3,399 Noncontrolling Interests as of June 30, December 31, 2018 2017 Edgewater $ 57,386 $ 58,568 Other 11 14 Total $ 57,397 $ 58,582

Incentive Plans (Tables)

Incentive Plans (Tables)	6 Months Ended
	Jun. 30, 2018
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 DSUs) within the Company’s accompanying condensed consolidated statements of operations for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Share-based incentive awards: RSUs $ 55,635 $ 54,354 $ 116,522 $ 110,295 PRSUs 17,051 16,417 28,018 28,199 Restricted Stock 12,600 13,161 23,373 22,810 DSUs 863 771 959 848 Total $ 86,149 $ 84,703 $ 168,872 $ 162,152
Summary of LFI and Other Similar Deferred Compensation Arrangements	The following is a summary of activity relating to LFI and other similar deferred compensation arrangements during the six month periods ended June 30, 2018 and 2017: Prepaid Compensation Asset Compensation Liability Balance, January 1, 2018 $ 60,355 $ 182,301 Granted 104,551 104,551 Settled - (84,422 ) Forfeited (618 ) (876 ) Amortization (50,057 ) - Change in fair value related to: Decrease in fair value of underlying investments - (1,935 ) Adjustment for estimated forfeitures - 2,330 Other (1,424 ) (1,105 ) Balance, June 30, 2018 $ 112,807 $ 200,844 Prepaid Compensation Asset Compensation Liability Balance, January 1, 2017 $ 49,650 $ 170,388 Granted 77,580 77,580 Settled - (95,633 ) Forfeited (585 ) (933 ) Amortization (39,503 ) - Change in fair value related to: Increase in fair value of underlying investments - 13,106 Adjustment for estimated forfeitures - 2,138 Other 942 1,312 Balance, June 30, 2017 $ 88,084 $ 167,958 The following is a summary of the impact of LFI and other similar deferred compensation arrangements on “compensation and benefits” expense within the accompanying condensed consolidated statements of operations for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended Six Months Ended June 30, June 30, 2018 2017 2018 2017 Amortization, net of forfeitures $ 36,293 $ 28,310 $ 52,129 $ 41,293 Change in the fair value of underlying investments (499 ) 5,753 (1,935 ) 13,106 Total $ 35,794 $ 34,063 $ 50,194 $ 54,399
Restricted Stock Units and Deferred Stock Units [Member]
Schedule of Activity Relating to Share-based Awards	The following is a summary of activity relating to RSUs and DSUs during the six month periods ended June 30, 2018 and 2017: RSUs DSUs Units Weighted Average Grant Date Fair Value Units Weighted Average Grant Date Fair Value Balance, January 1, 2018 12,919,846 $ 40.23 278,422 $ 37.46 Granted (including 636,207 RSUs relating to dividend participation) 3,974,389 $ 54.07 36,744 $ 52.18 Forfeited (105,853 ) $ 44.55 - - Vested (5,542,633 ) $ 42.86 - - Balance, June 30, 2018 11,245,749 $ 43.78 315,166 $ 39.18 Balance, January 1, 2017 11,698,138 $ 40.65 276,725 $ 36.05 Granted (including 739,079 RSUs relating to dividend participation) 5,134,126 $ 43.07 38,315 $ 44.30 Forfeited (92,011 ) $ 39.98 - - Vested (3,937,970 ) $ 45.36 (43,465 ) $ 35.77 Balance, June 30, 2017 12,802,283 $ 40.17 271,575 $ 37.26
Restricted Stock Awards Class A [Member]
Schedule of Activity Relating to Share-based Awards	The following is a summary of activity related to shares of restricted Class A common stock associated with compensation arrangements during the six month periods ended June 30, 2018 and 2017: Restricted Shares Weighted Average Grant Date Fair Value Balance, January 1, 2018 1,938,160 $ 40.54 Granted 529,987 $ 54.45 Forfeited (26,222 ) $ 47.00 Vested (848,187 ) $ 44.24 Balance, June 30, 2018 1,593,738 $ 43.09 Balance, January 1, 2017 1,655,073 $ 40.95 Granted 841,355 $ 42.58 Forfeited (32,568 ) $ 41.96 Vested (458,814 ) $ 45.57 Balance, June 30, 2017 2,005,046 $ 40.56
PRSUs [Member]
Schedule of Activity Relating to Share-based Awards	The following is a summary of activity relating to PRSUs during the six month periods ended June 30, 2018 and 2017: PRSUs Weighted Average Grant Date Fair Value Balance, January 1, 2018 1,591,693 $ 42.46 Granted (a) 399,869 $ 56.80 Vested (799,402 ) $ 46.74 Balance, June 30, 2018 1,192,160 $ 44.39 Balance, January 1, 2017 1,590,756 $ 40.76 Granted (a) 458,113 $ 43.76 Vested (825,565 ) $ 42.27 Balance, June 30, 2017 1,223,304 $ 40.86 (a) Represents PRSU awards granted during the relevant year at the target payout level.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost (Credit)	The following table summarizes the components of net periodic benefit cost (credit) related to the Company’s pension plans for the three month and six month periods ended June 30, 2018 and 2017: Three Months Ended June 30, 2018 2017 Components of Net Periodic Benefit Cost (Credit): Service cost $ 223 $ 335 Interest cost 3,977 4,086 Expected return on plan assets (7,583 ) (6,455 ) Amortization of: Prior service cost - - Net actuarial loss (gain) 1,245 1,552 Net periodic benefit cost (credit) $ (2,138 ) $ (482 ) Six Months Ended June 30, 2018 2017 Components of Net Periodic Benefit Cost (Credit): Service cost $ 453 $ 675 Interest cost 8,039 8,067 Expected return on plan assets (15,366 ) (12,560 ) Amortization of: Prior service cost - 30 Net actuarial loss (gain) 2,523 2,884 Net periodic benefit cost (credit) $ (4,351 ) $ (904 )

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets	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 Six Months Ended June 30, June 30, 2018 2017 2018 2017 Financial Advisory Net Revenue $ 419,468 $ 410,632 $ 827,935 $ 746,316 Operating Expenses 324,287 311,285 646,795 570,647 Operating Income $ 95,181 $ 99,347 $ 181,140 $ 175,669 Asset Management Net Revenue $ 352,588 $ 309,878 $ 706,871 $ 593,241 Operating Expenses 229,561 215,901 459,230 404,652 Operating Income $ 123,027 $ 93,977 $ 247,641 $ 188,589 Corporate Net Revenue $ (17,417 ) $ (4,484 ) $ (26,906 ) $ (1,054 ) Operating Expenses 8,977 13,594 23,109 34,946 Operating Loss $ (26,394 ) $ (18,078 ) $ (50,015 ) $ (36,000 ) Total Net Revenue $ 754,639 $ 716,026 $ 1,507,900 $ 1,338,503 Operating Expenses 562,825 540,780 1,129,134 1,010,245 Operating Income $ 191,814 $ 175,246 $ 378,766 $ 328,258 As Of June 30, 2018 December 31, 2017 Total Assets Financial Advisory $ 855,321 $ 817,185 Asset Management 709,833 756,398 Corporate 2,505,465 2,726,990 Total $ 4,070,619 $ 4,300,573

Organization and Basis of Pre41

Organization and Basis of Presentation - Additional Information (Detail) - Segment	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Organization And Basis Of Presentation [Line Items]
Governing operating agreement, date	Oct. 26, 2015
Number of business segments	2
Lazard Ltd [Member]
Organization And Basis Of Presentation [Line Items]
Percentage of common membership interests held	100.00%	100.00%

Recent Accounting Developments

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
U.S. federal statutory income tax rate		21.00%	35.00%
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Effect of the reclassification of contract costs from net revenue to expenses	$ 24,053	$ 47,609
Effect of reclassification of costs from revenue to operating expenses	$ 24,053	$ 47,609

Revenue Recognition - Represent

Revenue Recognition - Representation of Performance Obligations Relate to Nature, Amount, Timing and Uncertainty of Revenue and Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Financial Advisory Segment [Member]
Disaggregation Of Revenue [Line Items]
Net Revenue	$ 419,468	$ 827,935
Asset Management Segment [Member]
Disaggregation Of Revenue [Line Items]
Net Revenue	352,588	706,871
Asset Management Segment [Member] | Management Fees and Other [Member]
Disaggregation Of Revenue [Line Items]
Net Revenue	340,160	688,844
Asset Management Segment [Member] | Incentive Fees [Member]
Disaggregation Of Revenue [Line Items]
Net Revenue	$ 12,428	$ 18,027

Receivables - Schedule of Activ

Receivables - Schedule of Activity in Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Allowance For Doubtful Accounts Receivable Rollforward
Allowance for doubtful accounts receivables, Beginning balance	$ 38,505	$ 29,662	$ 23,692	$ 16,386
Bad debt expense, net of recoveries	666	180	16,618	13,831
Charge-offs, foreign currency translation and other adjustments	(4,265)	(4,748)	(5,404)	(5,123)
Allowance for doubtful accounts receivables, Ending balance	$ 34,906	$ 25,094	$ 34,906	$ 25,094

Receivables - Additional Inform

Receivables - Additional Information (Detail) - USD ($)	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables past due or deemed uncollectible	$ 42,384,000		$ 34,865,000
Interest-bearing financing fee receivables	74,668,000		80,536,000
Lazard Ltd subsidiaries	106,124,000		17,135,000
Allowance for doubtful accounts receivables	34,906,000	$ 38,505,000	23,692,000	$ 25,094,000	$ 29,662,000	$ 16,386,000
Aggregate carrying amount of non-interest bearing receivables	662,784,000		508,143,000
Interest-Bearing Receivables [Member] | Lazard Ltd Subsidiaries [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lazard Ltd subsidiaries	83,069,000		72,000
Financing Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts receivables	$ 0		$ 0

Investments - Company's Investm

Investments - Company's Investments and Securities Sold, Not Yet Purchased (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Total investments	$ 505,194	$ 427,186
Investments, at fair value	504,664	426,630
Securities sold, not yet purchased, at fair value (included in "other liabilities")	4,419	7,338
Interest-bearing Deposits [Member]
Schedule of Investments [Line Items]
Total investments	530	556
Debt [Member]
Schedule of Investments [Line Items]
Total investments	74,583	6
Investments, at fair value	74,583	6
Equities [Member]
Schedule of Investments [Line Items]
Total investments	39,818	45,257
Investments, at fair value	39,818	45,257
Alternative Investment Funds [Member]
Schedule of Investments [Line Items]
Total investments	26,097	20,993
Investments, at fair value	26,097	20,993
Debt Funds [Member]
Schedule of Investments [Line Items]
Total investments	87,529	84,077
Investments, at fair value	87,529	84,077
Equity Funds [Member]
Schedule of Investments [Line Items]
Total investments	209,379	199,618
Investments, at fair value	209,379	199,618
Private Equity Funds [Member]
Schedule of Investments [Line Items]
Total investments	67,258	76,679
Investments, at fair value	67,258	76,679
Funds Total [Member]
Schedule of Investments [Line Items]
Total investments	$ 390,263	$ 381,367

Investments - Company's Inves47

Investments - Company's Investments and Securities Sold, Not Yet Purchased (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Investments	$ 505,194	$ 427,186
Alternative Investment Funds [Member]
Schedule of Investments [Line Items]
Investments	26,097	20,993
Alternative Investment Funds [Member] | Lazard Fund Interests [Member]
Schedule of Investments [Line Items]
Investments	11,898	11,213
Debt Funds [Member]
Schedule of Investments [Line Items]
Investments	87,529	84,077
Debt Funds [Member] | Lazard Fund Interests [Member]
Schedule of Investments [Line Items]
Investments	57,444	48,391
Equity Funds [Member]
Schedule of Investments [Line Items]
Investments	209,379	199,618
Equity Funds [Member] | Lazard Fund Interests [Member]
Schedule of Investments [Line Items]
Investments	$ 147,862	$ 131,893

Investments - Additional Inform

Investments - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018
Minimum [Member] | Interest-bearing Deposits [Member]
Schedule of Investments [Line Items]
Deposits maturity period	3 months
Minimum [Member] | Debt [Member] | U.S. Treasury Securities [Member]
Schedule of Investments [Line Items]
US Treasury securities maturity period	3 months
Maximum [Member] | Interest-bearing Deposits [Member]
Schedule of Investments [Line Items]
Deposits maturity period	1 year
Maximum [Member] | Debt [Member] | U.S. Treasury Securities [Member]
Schedule of Investments [Line Items]
US Treasury securities maturity period	1 year

Investments - Schedule of Tradi

Investments - Schedule of Trading Securities Net Unrealized Investment Gains and Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Realized Or Unrealized Gain Loss On Trading Securities [Abstract]
Net unrealized investment gains (losses)	$ (5,864)	$ 7,803	$ (15,155)	$ 20,983

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Classification of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis and Investments Measured at NAV (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	$ 504,664	$ 426,630
Total Derivative Assets	6,399	3,732
Total investments measured at fair value	511,063	430,362
Securities sold, not yet purchased	4,419	7,338
Contingent consideration liability	3,470	4,656
Total Derivative Liabilities	202,975	198,417
Total of Liabilities Measured at Fair Value	210,864	210,411
Fair Value, Measurements, Recurring [Member] | NAV [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total investments measured at fair value	68,247	80,378
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total investments measured at fair value	434,788	344,660
Securities sold, not yet purchased	4,419	7,338
Total of Liabilities Measured at Fair Value	4,419	7,338
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total Derivative Assets	6,399	3,732
Total investments measured at fair value	6,399	3,732
Total Derivative Liabilities	202,975	198,417
Total of Liabilities Measured at Fair Value	202,975	198,417
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total investments measured at fair value	1,629	1,592
Contingent consideration liability	3,470	4,656
Total of Liabilities Measured at Fair Value	3,470	4,656
Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	74,583	6
Debt [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	74,583	6
Equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	39,818	45,257
Equities [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	38,189	43,665
Equities [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	1,629	1,592
Alternative Investment Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	26,097	20,993
Alternative Investment Funds [Member] | Fair Value, Measurements, Recurring [Member] | NAV [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	929	3,640
Alternative Investment Funds [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	25,168	17,353
Debt Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	87,529	84,077
Debt Funds [Member] | Fair Value, Measurements, Recurring [Member] | NAV [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	7	6
Debt Funds [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	87,522	84,071
Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	209,379	199,618
Equity Funds [Member] | Fair Value, Measurements, Recurring [Member] | NAV [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	53	53
Equity Funds [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	209,326	199,565
Private Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	67,258	76,679
Private Equity Funds [Member] | Fair Value, Measurements, Recurring [Member] | NAV [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments	$ 67,258	$ 76,679

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Assets and Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Assets:
Beginning Balance	$ 1,599	$ 1,537	$ 1,592	$ 1,508
Net Unrealized/Realized Gains/Losses Included In Earnings	62	(128)	61	(126)
Purchases/Acquisitions	0	1,661	1	1,661
Sales/Dispositions	0	0	0	(8)
Foreign Currency Translation Adjustments	(32)	2	(25)	37
Ending Balance	1,629	3,072	1,629	3,072
Liabilities:
Beginning Balance	4,661	4,078	4,656	3,364
Net Unrealized/Realized Gains/Losses Included In Earnings	(1,191)	30	(1,186)	744
Purchases/Acquisitions	0	0	0	0
Sales/Dispositions	0	0	0	0
Foreign Currency Translation Adjustments	0	0	0	0
Ending Balance	3,470	4,108	3,470	4,108
Contingent Consideration Liability [Member]
Liabilities:
Beginning Balance	4,661	4,078	4,656	3,364
Net Unrealized/Realized Gains/Losses Included In Earnings	(1,191)	30	(1,186)	744
Purchases/Acquisitions	0	0	0	0
Sales/Dispositions	0	0	0	0
Foreign Currency Translation Adjustments	0	0	0	0
Ending Balance	3,470	4,108	3,470	4,108
Equities [Member]
Assets:
Beginning Balance	1,599	1,537	1,592	1,508
Net Unrealized/Realized Gains/Losses Included In Earnings	62	(128)	61	(126)
Purchases/Acquisitions	0	1,661	1	1,661
Sales/Dispositions	0	0	0	(8)
Foreign Currency Translation Adjustments	(32)	2	(25)	37
Ending Balance	$ 1,629	$ 3,072	$ 1,629	$ 3,072

Fair Value Measurements - Sum52

Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Assets and Liabilities (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equities [Member]
Fair Value of Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Net unrealized gains (losses)	$ 62	$ (128)	$ 61	$ (128)
Contingent Consideration Liability [Member]
Fair Value of Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Net unrealized (gains) losses	$ (1,191)	$ 30	$ (1,186)	$ 744

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Fair Value Option Quantitative Disclosures [Line Items]
Transfers between Level 1, 2 and 3 in fair value measurement hierarchy	$ 0	$ 0	$ 0	$ 0
Unfunded Commitments	8,650,000		8,650,000		$ 10,300,000
EGCP III [Member]
Fair Value Option Quantitative Disclosures [Line Items]
Unfunded Commitments	$ 7,847,000		$ 7,847,000
End of the investment period			Oct. 12, 2016
Remaining obligation date			Oct. 12, 2023

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Certain Investments Based on NAV (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 68,247	$ 80,378
Unfunded Commitments	8,650	10,300
Hedge Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 332	$ 2,517
Investments Redeemable, Redemption Notice Period	60 days
Hedge Funds [Member] | Monthly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	100.00%	5.00%
Hedge Funds [Member] | Quarterly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent		92.00%
Hedge Funds [Member] | Weekly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent		3.00%
Hedge Funds [Member] | Minimum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period		30 days
Hedge Funds [Member] | Maximum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period		60 days
Funds of Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 25	$ 528
Investments Redeemable, Redemption Notice Period	90 days
Funds of Funds [Member] | Monthly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent		97.00%
Funds of Funds [Member] | Quarterly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	100.00%	3.00%
Funds of Funds [Member] | Minimum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period		30 days
Funds of Funds [Member] | Maximum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period		90 days
Other [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 572	$ 595
Other [Member] | Monthly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	94.00%	94.00%
Other [Member] | Daily [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	6.00%	6.00%
Other [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
Other [Member] | Maximum [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Redemption Notice Period	60 days	60 days
Debt Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 7	$ 6
Investments Redeemable, Redemption Notice Period	30 days	30 days
Debt Funds [Member] | Daily [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	100.00%	100.00%
Equity Funds [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 53	$ 53
Equity Funds [Member] | Monthly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	49.00%	50.00%
Equity Funds [Member] | Quarterly [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	32.00%	32.00%
Equity Funds [Member] | Daily [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Investments Redeemable, Percent	19.00%	18.00%
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	90 days
Private Equity Funds [Member] | Equity Growth [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 67,258	$ 76,679
Unfunded Commitments	$ 8,650	$ 10,300
% of Fair Value Not Redeemable	100.00%	100.00%
Estimated Liquidation Period of Investments Not Redeemable, % Next 5 Years	18.00%	16.00%
Estimated Liquidation Period of Investments Not Redeemable, % 5-10 Years	39.00%	38.00%
Estimated Liquidation Period of Investments Not Redeemable, % Thereafter	43.00%	46.00%

Fair Value Measurements - Fai55

Fair Value Measurements - Fair Value of Certain Investments Based on NAV (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitments	$ 8,650	$ 10,300
Private Equity Funds [Member] | Consolidated But Not Owned [Member]
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items]
Unfunded Commitments	$ 15,517	$ 5,902

Derivatives - Fair Values of De

Derivatives - Fair Values of Derivatives Reported on Condensed Consolidated Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 6,399	$ 3,732
Derivative Liabilities	202,975	198,417
Forward Foreign Currency Exchange Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	1,193	3,314
Derivative Liabilities	2,122	4,846
Total Return Swaps and Other [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	5,206	418
Derivative Liabilities	9	11,270
LFI and Other Similar Deferred Compensation Arrangements [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 200,844	$ 182,301	$ 167,958	$ 170,388

Derivatives - Fair Values of 57

Derivatives - Fair Values of Derivatives Reported on Condensed Consolidated Statements of Financial Condition (Parenthetical) (Detail) - Total Return Swaps [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross derivative assets	$ 5,789	$ 469
Gross derivative liability	592	11,321
Cash collateral pledged for total return swaps	$ 1,216	$ 17,616

Derivatives - Net Gains (Losses

Derivatives - Net Gains (Losses) with Respect to Derivative Instruments Not Designated as Hedging Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives instruments	$ 7,525	$ (15,980)	$ 8,134	$ (27,246)
Forward Foreign Currency Exchange Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedging instruments	6,236	(6,630)	3,753	(5,158)
LFI and Other Similar Deferred Compensation Arrangements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives not designated as hedging instruments	499	(5,753)	1,935	(13,106)
Total Return Swaps and Other [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivatives designated as hedging instruments	$ 790	$ (3,597)	$ 2,446	$ (8,982)

Property - Components of Proper

Property - Components of Property (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 539,598	$ 521,644
Less - Accumulated depreciation and amortization	324,863	317,816
Property	214,735	203,828
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 147,669	151,912
Property, plant and equipment, useful life	33 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 185,680	173,102
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	20 years
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 192,752	183,510
Furniture and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Furniture and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	10 years
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 13,497	$ 13,120

Goodwill and Other Intangible60

Goodwill and Other Intangible Assets - Components of Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	$ 355,933	$ 362,760	$ 360,092	$ 352,124
Other intangible assets (net of accumulated amortization)	4,754	5,274
Goodwill and other intangible assets, Total	$ 360,687	$ 368,034

Goodwill and Other Intangible61

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 355,933	$ 360,092	$ 355,933	$ 360,092	$ 362,760	$ 352,124
Amortization of intangible assets	653	$ 433	1,270	$ 867
Financial Advisory Segment [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	291,392		291,392		298,219
Asset Management Segment [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 64,541		$ 64,541		$ 64,541

Goodwill and Other Intangible62

Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning Balance	$ 362,760	$ 352,124
Foreign currency translation adjustments	(6,827)	7,968
Ending Balance	$ 355,933	$ 360,092

Goodwill and Other Intangible63

Goodwill and Other Intangible Assets - Gross Cost and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, Gross Cost	$ 67,226	$ 66,476
Other intangible assets, Accumulated Amortization	62,472	61,202
Other intangible assets, Net Carrying Amount	4,754	5,274
Success/Incentive Fees [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, Gross Cost	33,040	33,040
Other intangible assets, Accumulated Amortization	29,060	27,927
Other intangible assets, Net Carrying Amount	3,980	5,113
Management Fees, Customer Relationships and Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, Gross Cost	34,186	33,436
Other intangible assets, Accumulated Amortization	33,412	33,275
Other intangible assets, Net Carrying Amount	$ 774	$ 161

Goodwill and Other Intangible64

Goodwill and Other Intangible Assets - Estimated Future Amortization Expense (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2018 (July 1 through December 31)	$ 1,120
2,019	1,648
2,020	1,648
2,021	150
2,022	150
2,023	38
Total amortization expense	$ 4,754

Goodwill and Other Intangible65

Goodwill and Other Intangible Assets - Estimated Future Amortization Expense (Parenthetical) (Detail)	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Percentage of intangible asset amortization attributable to non-controlling interests	37.00%

Senior Debt - Senior Debt (Deta

Senior Debt - Senior Debt (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Senior Debt, Outstanding Principal	$ 1,200,000,000	$ 1,200,000,000
Senior Debt, Outstanding Unamortized Debt Costs	8,723,000	9,617,000
Senior Debt, Outstanding Carrying Value	1,191,277,000	1,190,383,000
Lazard Group 4.25% Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 500,000,000
Senior Debt, Maturity Date	Nov. 14, 2020
Senior Debt, Annual Interest Rate	4.25%
Senior Debt, Outstanding Principal	$ 500,000,000	500,000,000
Senior Debt, Outstanding Unamortized Debt Costs	2,187,000	2,647,000
Senior Debt, Outstanding Carrying Value	497,813,000	497,353,000
Lazard Group 3.75% Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 400,000,000
Senior Debt, Maturity Date	Feb. 13, 2025
Senior Debt, Annual Interest Rate	3.75%
Senior Debt, Outstanding Principal	$ 400,000,000	400,000,000
Senior Debt, Outstanding Unamortized Debt Costs	3,124,000	3,361,000
Senior Debt, Outstanding Carrying Value	396,876,000	396,639,000
Lazard Group 3.625% Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 300,000,000
Senior Debt, Maturity Date	Mar. 1, 2027
Senior Debt, Annual Interest Rate	3.625%
Senior Debt, Outstanding Principal	$ 300,000,000	300,000,000
Senior Debt, Outstanding Unamortized Debt Costs	3,412,000	3,609,000
Senior Debt, Outstanding Carrying Value	$ 296,588,000	$ 296,391,000

Senior Debt - Senior Debt (Pare

Senior Debt - Senior Debt (Parenthetical) (Detail)	6 Months Ended
	Jun. 30, 2018
Lazard Group 4.25% Senior Notes [Member]
Debt Instrument [Line Items]
Senior notes interest rate	4.25%
Original Maturity Date	Nov. 14, 2020
Effective interest rates of senior notes	4.43%
Lazard Group 3.75% Senior Notes [Member]
Debt Instrument [Line Items]
Senior notes interest rate	3.75%
Original Maturity Date	Feb. 13, 2025
Effective interest rates of senior notes	3.87%
Lazard Group 3.625% Senior Notes [Member]
Debt Instrument [Line Items]
Senior notes interest rate	3.625%
Original Maturity Date	Mar. 1, 2027
Effective interest rates of senior notes	3.76%

Senior Debt - Additional Inform

Senior Debt - Additional Information (Detail) - USD ($)	Sep. 25, 2015	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Senior debt		$ 1,191,277,000	$ 1,190,383,000
Unused Lines of Credit [Member]
Debt Instrument [Line Items]
Unused lines of credit		169,000,000
Senior Debt [Member]
Debt Instrument [Line Items]
Senior debt		1,191,277,000	1,190,383,000
Fair value of senior debt		1,183,000,000	1,230,000,000
LFB [Member] | Unused Lines of Credit [Member]
Debt Instrument [Line Items]
Unused lines of credit		17,000,000
Amended and Restated Credit Agreement [Member]
Debt Instrument [Line Items]
Senior revolving credit facility	$ 150,000,000
Duration of senior revolving credit facility, in years	5 years
Expiration of credit facility	2020-09
Outstanding credit facility		$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2018
Other Commitments [Line Items]
Guarantees indemnifications		$ 2,750,000
Collateral/counter-guarantees		2,750,000
LFB [Member]
Other Commitments [Line Items]
Other commitments		0
LFNY [Member]
Other Commitments [Line Items]
Other commitments		$ 0
Business Acquisitions [Member]
Other Commitments [Line Items]
Number of contingent additional shares earned		0
Business Acquisitions [Member] | Class A Common Stock [Member]
Other Commitments [Line Items]
Common stock issued and issuable	60,817
Business Acquisitions [Member] | Class A Common Stock [Member] | Maximum [Member]
Other Commitments [Line Items]
Contingent shares issuable upon satisfaction of performance thresholds	210,431

Members' Equity - Additional In

Members' Equity - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Schedule Of Stockholders Equity [Line Items]
Share repurchase remaining authorization	$ 324,589
October, 2017 [Member]
Schedule Of Stockholders Equity [Line Items]
Share repurchase remaining authorization	$ 24,589
Expiration	Dec. 31, 2019
April, 2018 [Member]
Schedule Of Stockholders Equity [Line Items]
Share repurchase remaining authorization	$ 300,000
Expiration	Dec. 31, 2020
Lazard Ltd Subsidiaries [Member]
Schedule Of Stockholders Equity [Line Items]
Distribution to members	$ 265,592	$ 244,722
Executive Officers [Member]
Schedule Of Stockholders Equity [Line Items]
Shares repurchased, value	$ 16,400	$ 14,700

Members' Equity - Schedule of S

Members' Equity - Schedule of Share Repurchase Authorized by Board of Directors (Detail)	6 Months Ended
	Jun. 30, 2018USD ($)
February, 2015 [Member] | Class A Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Authorization	$ 150,000,000
Expiration	Dec. 31, 2016
January, 2016 [Member] | Class A Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Authorization	$ 200,000,000
Expiration	Dec. 31, 2017
April, 2016 [Member] | Class A Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Authorization	$ 113,182,000
Expiration	Dec. 31, 2017
November, 2016 [Member] | Class A Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Authorization	$ 236,000,000
Expiration	Dec. 31, 2018
October, 2017 [Member]
Equity, Class of Treasury Stock [Line Items]
Expiration	Dec. 31, 2019
October, 2017 [Member] | Class A Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Authorization	$ 200,000,000
Expiration	Dec. 31, 2019
April, 2018 [Member]
Equity, Class of Treasury Stock [Line Items]
Expiration	Dec. 31, 2020
April, 2018 [Member] | Class A Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Repurchase Authorization	$ 300,000,000
Expiration	Dec. 31, 2020

Members' Equity - Schedule of72

Members' Equity - Schedule of Share Repurchase Program (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Share Repurchase Program [Abstract]
Number of Shares Purchased	4,147,526	4,268,479
Average Price Per Share	$ 53.96	$ 43.32

Members' Equity - Accumulated O

Members' Equity - Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance					$ 906,900	[1]	$ 736,140	[2]
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	$ (31,499)		$ 18,070		(16,502)		31,960
Balance	781,427	[1]	708,942	[2]	781,427	[1]	708,942	[2]
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(24,841)		(96,007)		(43,790)		(109,306)
Other comprehensive income (loss) before reclassifications	(40,576)		25,323		(21,627)		38,622
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(40,576)		25,323		(21,627)		38,622
Balance	(65,417)		(70,684)		(65,417)		(70,684)
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(155,418)		(160,880)		(151,466)		(161,471)
Other comprehensive income (loss) before reclassifications	8,300		(8,609)		3,286		(9,104)
Adjustments for items reclassified to earnings, net of tax	777		1,356		1,839		2,442
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	9,077		(7,253)		5,125		(6,662)
Balance	(146,341)		(168,133)		(146,341)		(168,133)
Total AOCI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(180,259)		(256,887)		(195,256)		(270,777)
Other comprehensive income (loss) before reclassifications	(32,276)		16,714		(18,341)		29,518
Adjustments for items reclassified to earnings, net of tax	777		1,356		1,839		2,442
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(31,499)		18,070		(16,502)		31,960
Balance	(211,758)		(238,817)		(211,758)		(238,817)
AOCI Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			(2)				(2)
Other comprehensive income (loss) before reclassifications	(1)		1		(1)		1
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(1)		1		(1)		1
Balance	(1)		(1)		(1)		(1)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(180,259)		(256,885)		(195,256)	[1]	(270,775)	[2]
Other comprehensive income (loss) before reclassifications	(32,275)		16,713		(18,340)		29,517
Adjustments for items reclassified to earnings, net of tax	777		1,356		1,839		2,442
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(31,498)		18,069		(16,501)		31,959
Balance	$ (211,757)	[1]	$ (238,816)	[2]	$ (211,757)	[1]	$ (238,816)	[2]
[1]	As of January 1, 2018 and June 30, 2018, in addition to profit participation interests, there were two managing member interests.
[2]	As of January 1, 2017 and June 30, 2017, in addition to profit participation interests, there were two managing member interests.

Members' Equity - Adjustments f

Members' Equity - Adjustments for Items Reclassified Out of AOCI (Detail) - Accumulated Defined Benefit Plans Adjustment [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization relating to employee benefit plans	$ 1,245	$ 1,552	$ 2,523	$ 2,914
Less - related income taxes	468	196	684	472
Total reclassifications, net of tax	$ 777	$ 1,356	$ 1,839	$ 2,442

Members' Equity - Net Income At

Members' Equity - Net Income Attributable to Noncontrolling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Change In Ownership Interest [Line Items]
Net Income Attributable to Noncontrolling Interests	$ 1,416	$ 522	$ 3,385	$ 3,399
Noncontrolling interests	57,397		57,397		$ 58,582
Edgewater [Member]
Change In Ownership Interest [Line Items]
Net Income Attributable to Noncontrolling Interests	1,415	520	3,383	3,397
Noncontrolling interests	57,386		57,386		58,568
Other [Member]
Change In Ownership Interest [Line Items]
Net Income Attributable to Noncontrolling Interests	1	$ 2	2	$ 2
Noncontrolling interests	$ 11		$ 11		$ 14

Incentive Plans - Additional In

Incentive Plans - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Apr. 24, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend participation rights required the issuance of RSUs	636,207	739,079
Lazard Fund Interests [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, years	10 months 24 days
Non-Executive [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annual compensation received by directors in the form of DSUs	55.00%
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock conversion basis	one-for-one
Grant date fair value, amortized periods	generally one-third after two years, and the remaining two-thirds after the third year
Unrecognized compensation expense	$ 203,205
Unrecognized compensation expense, years	10 months 24 days
DSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual compensation paid in DSUs	30,463	31,280
Units granted under the directors deferred unit plan	6,281	7,035
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 31,084
Unrecognized compensation expense, years	9 months 18 days
PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 12,594
Unrecognized compensation expense, years	10 months 24 days
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%
Descriptions of vesting period associated with PRSUs	PRSUs will vest on a single date approximately three years following the date of the grant
Vesting period of PRSUs granted	3 years
PRSU's target share distribution for Class A common stock, description	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 generally can range from zero to two times the target number.
Class A Common Stock [Member] | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Withholding taxes in lieu of share delivery	1,635,514	1,267,560
Delivery of common stock associated with stock awards	3,907,119	2,670,410
Class A Common Stock [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Withholding taxes in lieu of share delivery	289,831	135,528
Delivery of common stock associated with stock awards	558,356	323,286
Class A Common Stock [Member] | PRSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Withholding taxes in lieu of share delivery	91,962	126,264
Delivery of common stock associated with stock awards	707,440	699,301
Class A Common Stock [Member] | 2018 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized pertaining to share based compensation arrangements			30,000,000
Class A Common Stock [Member] | Awarded Under 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of outstanding Class A common stock	30.00%
Compensation plan expiration period	Apr. 24, 2018
Class A Common Stock [Member] | 2005 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized pertaining to share based compensation arrangements	25,000,000

Incentive Plans - Summary of Im

Incentive Plans - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based incentive awards:
Share-based incentive awards	$ 86,149	$ 84,703	$ 168,872	$ 162,152
RSUs [Member]
Share-based incentive awards:
Share-based incentive awards	55,635	54,354	116,522	110,295
PRSUs [Member]
Share-based incentive awards:
Share-based incentive awards	17,051	16,417	28,018	28,199
Restricted Stock [Member]
Share-based incentive awards:
Share-based incentive awards	12,600	13,161	23,373	22,810
DSUs [Member]
Share-based incentive awards:
Share-based incentive awards	$ 863	$ 771	$ 959	$ 848

Incentive Plans - Schedule of A

Incentive Plans - Schedule of Activity Relating to RSUs and DSUs (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
RSUs [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Units, Beginning Balance	12,919,846	11,698,138
Units, Granted	3,974,389	5,134,126
Units, Forfeited	(105,853)	(92,011)
Units, Vested	(5,542,633)	(3,937,970)
Units, Ending Balance	11,245,749	12,802,283
Weighted Average Grant Date Fair Value, Beginning Balance	$ 40.23	$ 40.65
Weighted Average Grant Date Fair Value, Granted	54.07	43.07
Weighted Average Grant Date Fair Value, Forfeited	44.55	39.98
Weighted Average Grant Date Fair Value, Vested	42.86	45.36
Weighted Average Grant Date Fair Value, Ending Balance	$ 43.78	$ 40.17
DSUs [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Units, Beginning Balance	278,422	276,725
Units, Granted	36,744	38,315
Units, Vested		(43,465)
Units, Ending Balance	315,166	271,575
Weighted Average Grant Date Fair Value, Beginning Balance	$ 37.46	$ 36.05
Weighted Average Grant Date Fair Value, Granted	52.18	44.30
Weighted Average Grant Date Fair Value, Vested		35.77
Weighted Average Grant Date Fair Value, Ending Balance	$ 39.18	$ 37.26

Incentive Plans - Schedule of79

Incentive Plans - Schedule of Activity Relating to RSUs and DSUs (Parenthetical) (Detail) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Dividend participation rights	636,207	739,079

Incentive Plans - Summary of Ac

Incentive Plans - Summary of Activity Related to Shares of Restricted Class A Common Stock (Detail) - Restricted Stock [Member] - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Share-based compensation arrangement by share-based payment award [Line Items]
Units, Beginning Balance	1,938,160	1,655,073
Units, Granted	529,987	841,355
Units, Forfeited	(26,222)	(32,568)
Units, Vested	(848,187)	(458,814)
Units, Ending Balance	1,593,738	2,005,046
Weighted Average Grant Date Fair Value, Beginning Balance	$ 40.54	$ 40.95
Weighted Average Grant Date Fair Value, Granted	54.45	42.58
Weighted Average Grant Date Fair Value, Forfeited	47	41.96
Weighted Average Grant Date Fair Value, Vested	44.24	45.57
Weighted Average Grant Date Fair Value, Ending Balance	$ 43.09	$ 40.56

Incentive Plans - Summary of 81

Incentive Plans - Summary of Activity Relating to PRSUs (Detail) - PRSUs [Member] - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Share-based compensation arrangement by share-based payment award [Line Items]
Units, Beginning Balance	1,591,693	1,590,756
Units, Granted	399,869	458,113
Units, Vested	(799,402)	(825,565)
Units, Ending Balance	1,192,160	1,223,304
Weighted Average Grant Date Fair Value, Beginning Balance	$ 42.46	$ 40.76
Weighted Average Grant Date Fair Value, Granted	56.80	43.76
Weighted Average Grant Date Fair Value, Vested	46.74	42.27
Weighted Average Grant Date Fair Value, Ending Balance	$ 44.39	$ 40.86

Incentive Plans - Summary of LF

Incentive Plans - Summary of LFI and Other Similar Deferred Compensation Arrangements (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Compensation Liability, Beginning Balance	$ 198,417
Compensation Liability, Ending Balance	202,975
LFI and Other Similar Deferred Compensation Arrangements [Member]
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Prepaid Compensation Asset, Beginning Balance	60,355	$ 49,650
Prepaid Compensation Asset, Granted	104,551	77,580
Prepaid Compensation Asset, Forfeited	(618)	(585)
Prepaid Compensation Asset, Amortization	(50,057)	(39,503)
Prepaid Compensation Asset, Other	(1,424)	942
Prepaid Compensation Asset, Ending Balance	112,807	88,084
Compensation Liability, Beginning Balance	182,301	170,388
Compensation Liability, Granted	104,551	77,580
Compensation Liability, Settled	(84,422)	(95,633)
Compensation Liability, Forfeited	(876)	(933)
Compensation Liability, (Decrease) Increase in fair value of underlying investments	(1,935)	13,106
Compensation Liability, Adjustment for estimated forfeitures	2,330	2,138
Compensation Liability, Other	(1,105)	1,312
Compensation Liability, Ending Balance	$ 200,844	$ 167,958

Incentive Plans - Summary of 83

Incentive Plans - Summary of Impact of LFI and Other Similar Deferred Compensation Arrangements (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share Based Compensation [Abstract]
Amortization, net of forfeitures	$ 36,293	$ 28,310	$ 52,129	$ 41,293
Change in the fair value of underlying investments	(499)	5,753	(1,935)	13,106
Total	$ 35,794	$ 34,063	$ 50,194	$ 54,399

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Detail) - Pension Plans [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Components of Net Periodic Benefit Cost (Credit):
Service cost	$ 223	$ 335	$ 453	$ 675
Interest cost	3,977	4,086	8,039	8,067
Expected return on plan assets	(7,583)	(6,455)	(15,366)	(12,560)
Amortization of:
Prior service cost				30
Net actuarial loss (gain)	1,245	1,552	2,523	2,884
Net periodic benefit cost (credit)	$ (2,138)	$ (482)	$ (4,351)	$ (904)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Jan. 01, 2017
Income Tax [Line Items]
U.S. federal statutory income tax rate			21.00%		35.00%
Income tax provisions	$ 31,445	$ 32,440	$ 50,060	$ 54,435
Effective income tax rates	16.40%	18.50%	13.20%	16.60%
Adjustments for New Accounting Principle [Member]
Income Tax [Line Items]
Income tax provisions			$ 14,085	$ 2,018
Deferred tax assets recorded for previously unrecognized excess tax benefits on share-based payment awards						$ 4,945
Deferred tax assets, valuation allowance						$ 12,090

Related Parties - Additional In

Related Parties - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Lazard Ltd subsidiaries	$ 106,124		$ 106,124		$ 17,135
Fees receivable	610,488		610,488		487,800
Asset Management Fees [Member]
Related Party Transaction [Line Items]
Net Revenue	335,891	$ 293,879	673,987	$ 566,803
Lazard Ltd Subsidiaries [Member]
Related Party Transaction [Line Items]
Interest income related to interest-bearing loans	200	10	221	143
Notes payable related parties current and noncurrent	62,036		62,036		64,203
Interest expense related to interest-bearing loans with subsidiaries	929	931	1,902	1,875
Sponsored Funds [Member]
Related Party Transaction [Line Items]
Fees receivable	84,565		84,565		69,107
Sponsored Funds [Member] | Asset Management Fees [Member]
Related Party Transaction [Line Items]
Net Revenue	170,680	$ 167,382	351,990	$ 307,959
Interest-Bearing Receivables [Member] | Lazard Ltd Subsidiaries [Member]
Related Party Transaction [Line Items]
Lazard Ltd subsidiaries	$ 83,069		$ 83,069		$ 72

Regulatory Authorities - Additi

Regulatory Authorities - Additional Information (Detail) - USD ($)	Jun. 30, 2018	Mar. 31, 2018
LFNY [Member]
Regulatory Requirements [Line Items]
Specified fixed percentage, minimum required capital	6.67%
Minimum net capital requirement as defined under exchange act	$ 100,000
Regulatory capital	109,681,000
Regulatory capital in excess of minimum requirement	$ 106,644,000
Aggregate indebtedness to net capital ratio	0.42
LFNY [Member] | Maximum [Member]
Regulatory Requirements [Line Items]
Aggregate indebtedness to net capital ratio	15
U.K. Subsidiaries [Member]
Regulatory Requirements [Line Items]
Regulatory capital	$ 166,717,000
Regulatory capital in excess of minimum requirement	148,324,000
CFLF [Member]
Regulatory Requirements [Line Items]
Regulatory capital	130,702,000
Regulatory capital in excess of minimum requirement	76,071,000
Combined European Regulated Group [Member]
Regulatory Requirements [Line Items]
Regulatory capital		$ 176,098,000
Regulatory capital in excess of minimum requirement		$ 63,607,000
Other U.S. and Non-U.S. Subsidiaries [Member]
Regulatory Requirements [Line Items]
Regulatory capital	158,343,000
Regulatory capital in excess of minimum requirement	$ 130,629,000

Segment Information - Segment's

Segment Information - Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net Revenue	$ 754,639	$ 716,026	$ 1,507,900	$ 1,338,503
Operating Expenses	562,825	540,780	1,129,134	1,010,245
Operating Income (Loss)	191,814	175,246	378,766	328,258
Total Assets	4,070,619		4,070,619		$ 4,300,573
Operating Segments [Member] | Financial Advisory Segment [Member]
Segment Reporting Information [Line Items]
Net Revenue	419,468	410,632	827,935	746,316
Operating Expenses	324,287	311,285	646,795	570,647
Operating Income (Loss)	95,181	99,347	181,140	175,669
Total Assets	855,321		855,321		817,185
Operating Segments [Member] | Asset Management Segment [Member]
Segment Reporting Information [Line Items]
Net Revenue	352,588	309,878	706,871	593,241
Operating Expenses	229,561	215,901	459,230	404,652
Operating Income (Loss)	123,027	93,977	247,641	188,589
Total Assets	709,833		709,833		756,398
Corporate [Member]
Segment Reporting Information [Line Items]
Net Revenue	(17,417)	(4,484)	(26,906)	(1,054)
Operating Expenses	8,977	13,594	23,109	34,946
Operating Income (Loss)	(26,394)	$ (18,078)	(50,015)	$ (36,000)
Total Assets	$ 2,505,465		$ 2,505,465		$ 2,726,990