Represents the net change of obligations incurred through that date and payable for obligations related to services received from employees such as accrued salaries, bonuses, payroll taxes and fringe benefits and the sum of other liabilities not individually reported in the financial statements or separately disclosed in the notes. Accrued Compensation And Benefits And Other Liabilities Accrued compensation and benefits and other liabilities Accrued Fees And Other Revenue Receivable Fees Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Less - Accumulated depreciation and amortization Property, accumulated amortization and depreciation Total accumulated other comprehensive income loss. Accumulated Other Comprehensive Income Loss Total AOCI Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax Employee benefit plans Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax Currency translation adjustments Accumulated Other Comprehensive Income Loss [Line Items] Accumulated Other Comprehensive Income Loss [Line Items] Accumulated Other Comprehensive Income Loss [Line Items] Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated other comprehensive loss, net of tax Total Lazard Group AOCI Accumulated Other Comprehensive Income Loss [Table] Accumulated Other Comprehensive Income Loss [Table] Accumulated Other Comprehensive Income Loss [Table] Accumulated other comprehensive income loss unamortized interest rate hedge amount. Accumulated Other Comprehensive Income Loss Unamortized Interest Rate Hedge Amount Interest rate hedge Accumulated Other Comprehensive Income [Member] Accumulated Other Comprehensive Income (Loss), Net of Tax [Member] Actuarial loss from remeasurement of pension plans. Actuarial Loss Actuarial loss Additional Authorized Amount For Share Repurchase Program Additional Authorized Amount For Share Repurchase Program Repurchase of additional aggregate cost Adjustment For Amortization Prepaid Compensation Asset, Amortization (including grants of awards to retirement-eligible recipients) Adjustment For Amortization [Abstract] Amortization of: Adjustments Noncash Items To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Noncash items included in net income: Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Amortization of share-based incentive compensation Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by (used in) operating activities: Aggregate amount of cash deposited with clearing organizations and other segregated cash. Aggregate Amount Of Cash Deposited With Clearing Organizations And Other Segregated Cash Account security arrangement Aggregate cost of shares/common membership interests purchased. Aggregate Cost Of Shares Common Membership Interests Purchased Aggregate cost of shares/common membership interests purchased Allowance For Doubtful Accounts Receivable Allowance for doubtful accounts receivable Alternative Investments Fair Value Disclosure Fair Value Amend and extend existing escrow. Amend And Extend Existing Escrow Amend and Extend Existing Escrow Amendment Flag Amendment Flag Amortization, grants of awards to retirement-eligible recipients. Amortization Grants Of Awards To Retirement Eligible Recipients Amortization, after impact of forfeitures Amortization of Deferred Expenses, Stock Units and Interest Rate Hedge. Amortization Of Deferred Expenses Stock Units And Interest Rate Hedge Amortization of deferred expenses, share-based incentive compensation and interest rate hedge Amortization Of Intangible Assets Amortization of intangible assets Amortization of intangible assets related to acquisitions Amortization of prepaid compensation asset weighted average recognition period. Amortization Of Prepaid Compensation Asset Weighted Average Recognition Period Amortization of prepaid compensation asset, weighted average recognition period, years Amount receivable related to referral fees for underwriting and private placement transactions. Amount Receivable Related To Referral Fees For Underwriting And Private Placement Transactions Amount receivable related to referral fees for underwriting and private placement transactions Amount receivables related to administrative and support services, and other receivables which include sublease income and reimbursement of expenses. Amount Receivables Related To Administrative And Support Services And Other Receivables Which Include Sublease Income And Reimbursement Of Expenses Amount receivables related to administrative and support services, and other receivables which include sublease income and reimbursement of expenses Amounts recorded relating to the administrative services agreement Amounts Recorded Relating To Administrative Services Agreement Amounts recorded relating to the administrative services agreement Amounts recorded relating to net referral fees for underwriting, private placement, and restructuring transactions. Amounts Recorded Relating To Net Referral Fees For Underwriting Private Placement And Restructuring Transactions Amounts recorded relating to net referral fees for underwriting, private placement, M&A and restructuring transactions Annual contributions to account security arrangement Annual Contributions To Account Security Arrangement Annual contributions to account security arrangement Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] Asset Management Fees Money management fees Asset Management [Member] Asset Management [Member] Asset management segment. Asset Management Segment [Member] Asset Management segment [Member] Assets Total Assets Total assets Assets [Abstract] ASSETS Assets: Assets Fair Value Disclosure Total Assets Awarded under two thousand eight plan. Awarded Under Two Thousand Eight Plan [Member] 2008 Plan [Member] Award Type [Axis] Award Type [Axis] Building [Member] Buildings [Member] Business Acquisition Contingent Consideration At Fair Value Aggregate fair value of the consideration recognized at the acquisition date Business Acquisition [Line Items] Business Acquisition [Line Items] Business acquisition number of common stock issued Business Acquisition Number Of Common Stock Issued Shares of Class A common stock issued Business acquisition number of common stock issued subject to earnout criteria and payable over time Business Acquisition Number Of Common Stock Issued Subject To Earnout Criteria And Payable Over Time Business acquisition number of common stock issued subject to earnout criteria and payable over time Business acquisitions and related equity transaction. Business Acquisitions And Related Equity Transaction [Abstract] Business acquisitions and related equity transactions: Business Acquisition Share Unrestricted Or Delivered Business Acquisition Share Unrestricted Or Delivered Business acquisition, shares unrestricted or delivered Business Combination Disclosure [Text Block] BUSINESS ACQUISITIONS Capital Lease Obligations Capital lease obligations Cash And Cash Equivalents At Carrying Value CASH AND CASH EQUIVALENTS-September 30 CASH AND CASH EQUIVALENTS-January 1 Cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS Cash And Securities Segregated Under Federal And Other Regulations Cash deposited with clearing organizations and other segregated cash Certain advances and referral fees. Certain Advances And Referral Fees Payables relating to certain advances and referral fees CFLF. Cflf [Member] CFLF [Member] Change in fair value of compensation liability. Change In Fair Value Of Compensation Liability Change in fair value of underlying investments Compensation Liability, Change in fair value of underlying investments Amount of charge-offs, foreign currency translation and other adjustments charged to the allowance for doubtful accounts. Charge Offs Foreign Currency Translation And Other Adjustments Charge-offs, foreign currency translation and other adjustments Class A Common Stock Delivered During Period Class A Common Stock Delivered During Period Class A common stock delivered during the period Class Of Stock [Domain] Class of Stock [Domain] COF 2. Cof Two [Member] COF 2 [Member] Commitments And Contingencies Commitments and contingencies Commitments And Contingencies Disclosure [Text Block] COMMITMENTS AND CONTINGENCIES Common Class A [Member] Class A common stock [Member] Common Class B [Member] Class B common stock [Member] Common membership interest. Common Membership Interest Common membership interest The cash outflow to repurchase common membership interests. Common Membership Interest Repurchased Repurchase of common membership interests from members of LAZ-MD Holdings Repurchase of common membership interests during the period. Common Membership Interest Repurchased During Period Value Repurchase of common membership interests from LAZ-MD Holdings Common membership interests held. Common Membership Interests Held Common membership interests held Common membership interests issued in connection with business acquisitions. Common Membership Interests Issued In Connection With Business Acquisitions Common membership interests issued Number of shares in common membership interests. Common Membership Interests Shares Common Membership Interests, Shares Outstanding Common membership voting power held in parent company by non-controlling interest. Common Membership Voting Power Held In Parent Common membership voting power held Number of shares of common stock held in the parent company, which are purchased for the purpose of granting the shares to senior employees as part of an employee stock option plan at the parent company. Common Stock Held In Parent Company Shares Lazard Ltd common stock, shares Value of common stock held in the Parent Company, which are purchased for the purpose of granting the shares to senior employees as part of an employee stock option plan at the Parent Company. Common Stock Held In Parent Company Value Lazard Ltd common stock, cost Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Table] Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Table] Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Table] Common Stock Par Or Stated Value Per Share Common stock, par value Common Stock Shares Issued Common stock, shares issued Common Stock Shares Outstanding Common stock, shares outstanding Company fund interests equities. Company Fund Interests Equities Lazard Fund Interests in equities Company fund interests fixed income funds. Company Fund Interests Fixed Income Funds Lazard Fund Interests in fixed income funds Company fund interests in alternative asset management funds fair value of investments. Company Fund Interests In Alternative Asset Management Funds Fair Value Of Investments Lazard Fund Interests in alternative asset management funds Company [Member] Company [Member] Lazard [Member] Component Of Other Operating Cost And Expense General [Axis] Component of Other Operating Cost and Expense [Axis] Component Of Other Operating Cost And Expense Name [Domain] Component of Other Operating Cost and Expense, Name [Domain] Comprehensive Income Net Of Tax COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD GROUP Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest LESS - COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO NONCONTROLLING INTERESTS Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest COMPREHENSIVE INCOME Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract] Comprehensive income (loss): Comprehensive Income Policy Policy [Text Block] Other Comprehensive Income Construction In Progress [Member] Construction in progress [Member] Contingencies And Commitments [Line Items] Contingencies And Commitments [Line Items] Contingencies And Commitments [Line Items] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contingent Consideration Earned Contingent Consideration Earned Additional contingent consideration earned Conversion Of Stock By Unique Description [Axis] Stock Conversion Description [Axis] Conversion Of Stock Name [Domain] Conversion of Stock, Name [Domain] Corporate [Member] Corporate [Member] Costs And Expenses Operating Expenses Total operating expenses Costs And Expenses [Abstract] OPERATING EXPENSES Cp I I [Member] Cp I I [Member] Cp II [Member] Current Fiscal Year End Date Current Fiscal Year End Date Debt Disclosure [Text Block] SENIOR AND SUBORDINATED DEBT Debt Instrument [Axis] Debt Instrument [Axis] Debt instrument excess of fair value over carrying value. Debt Instrument Excess Of Fair Value Over Carrying Value Fair value of senior debt in excess of the aggregate carrying value Debt Instrument Face Amount Senior debt, Initial Principal Amount Debt Instrument Fair Value Fair value of senior debt Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument Maturity Date Senior debt, Maturity Date Debt Instrument Name [Domain] Debt Instrument, Name [Domain] Debt Instrument Repurchased Face Amount Subordinated promissory note repurchased Debt Instrument [Table] Schedule of Long-term Debt Instruments [Table] Represents us and non us government debt other debt and interest bearing deposits. Debt Securities Debt Debt Securities [Member] Debt [Member] Deconsolidation of investment companies. Deconsolidation Of Investment Companies Deconsolidation of investment companies Deferred Compensation Arrangement With Individual Postretirement Benefits By Type Of Deferred Compensation [Axis] Postretirement Benefits, Type of Deferred Compensation [Axis] Deferred Compensation Arrangement With Individual Share Based Payments By Title Of Individual [Axis] Title of Individual [Axis] Deferred Compensation Arrangement With Individual Share Based Payments [Line Items] Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] Deferred stock unit. Deferred Stock Unit [Member] DSUs [Member] Defined Benefit Plan Actuarial Gain Loss Net actuarial loss Defined Benefit Plan Amortization Of Prior Service Cost Credit Prior service cost Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Estimated Future Employer Contributions In Current Fiscal Year Employer contribution in current fiscal year Defined benefit plan estimated yearly future employer contributions. Defined Benefit Plan Estimated Yearly Future Employer Contributions Contribution each year from 2012 through 2020 Defined Benefit Plan Expected Return On Plan Assets Expected return on plan assets Defined Benefit Plan Interest Cost Interest cost Defined Benefit Plan Net Periodic Benefit Cost Net periodic benefit cost Defined Benefit Plan Net Periodic Benefit Cost [Abstract] Components of Net Periodic Benefit Cost: Defined Benefit Plans Disclosures Defined Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans [Domain] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan Service Cost Service cost Defined Benefit Plan Settlements Benefit Obligation Settlement loss Defined Benefit Postretirement Health Coverage [Member] Post-Retirement Medical Plans [Member] Defined Contribution Plan Employer Discretionary Contribution Amount Pension plans contributions DSU's received under the Directors Fee Deferral Unit Plan Delivery Of Common Stock Associated With Stock Awards DSUs received under the Directors Fee Deferral Unit Plan Delivery of parent company common stock in connection with business acquisitions. Delivery Of Parent Company Common Stock In Connection With Business Acquisitions Delivery of Lazard Ltd Class A common stock Delivery of parent company common stock share based compensation and related tax benefits. Delivery Of Parent Company Common Stock Share Based Compensation And Related Tax Benefits Delivery of Lazard Ltd Class A common stock in connection with share-based incentive compensation and related tax benefit (expense) Deposits and other customer payables principally related to customer-related interest-bearing time and demand deposits, short-term inter-bank borrowing with registered banks and amounts due on collateralized borrowing activities. Deposits And Other Customer Payables Deposits and other customer payables The amount of expense recognized in the current period that reflects the allocation of the cost of property over the assets' useful lives. Depreciation And Amortization Of Property Depreciation and amortization of property Derivative Assets Derivative Assets Derivatives Derivative Contract Type [Domain] Derivative Contract Type [Domain] Derivative Fair Value Of Derivative Liability Compensation Liability, Balance, September 30, 2012 Compensation Liability, Balance, January 1, 2012 Derivative Financial Instruments Liabilities Fair Value Disclosure Derivatives Derivative Instrument Risk [Axis] Derivative Instrument Risk [Axis] Derivative Instruments And Hedging Activities Disclosure [Text Block] DERIVATIVES Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments Gain Loss [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net Gains (losses) on derivatives not designated as hedging instruments Derivative Liabilities Derivative Liabilities Derivative Liability Adjustment To Forfeiture Derivative Liability Adjustment To Forfeiture Compensation Liability, Adjustment for estimated forfeitures Derivative liability, amortization. Derivative Liability Amortization Compensation Liability, Amortization (including grants of awards to retirement-eligible recipients) Derivative liability, foreign currency translation and other adjustments. Derivative Liability Foreign Currency Translation And Other Adjustments Compensation Liability, Other Derivative liability forfeited. Derivative Liability Forfeited Compensation Liability, Forfeited Derivative liability, granted. Derivative Liability Granted Compensation Liability, Granted Derivative liability, vested. Derivative Liability Settled Compensation Liability, Settled Derivative [Line Items] Derivative [Line Items] Disclosure - BUSINESS ACQUISITIONS - Additional Information [Abstract] Disclosure Business Acquisitions Additional Information [Abstract] Disclosure - BUSINESS ACQUISITIONS - Additional Information [Abstract] Disclosure Commitments And Contingencies Additional Information [Abstract] Disclosure Commitments And Contingencies Additional Information [Abstract] Disclosure Commitments And Contingencies Additional Information [Abstract] Disclosure - DERIVATIVES - Fair Value of Derivatives Reported on Consolidated Statements of Financial Condition [Abstract] Disclosure Derivatives Fair Value Of Derivatives Reported On Consolidated Statements Of Financial Condition [Abstract] Disclosure - DERIVATIVES - Fair Value of Derivatives Reported on Consolidated Statements of Financial Condition [Abstract] Disclosure - DERIVATIVES - Net Gains (Losses) With Respect to Derivative Instruments Not Designated as Hedging Instruments [Abstract] Disclosure Derivatives Net Gains Losses With Respect To Derivative Instruments Not Designated As Hedging Instruments [Abstract] Disclosure - DERIVATIVES - Net Gains (Losses) With Respect to Derivative Instruments Not Designated as Hedging Instruments [Abstract] Disclosure Employee Benefit Plans Additional Information [Abstract] Disclosure Employee Benefit Plans Additional Information [Abstract] Disclosure Employee Benefit Plans Additional Information [Abstract] Disclosure - EMPLOYEE BENEFIT PLANS - Components of Net Benefit Cost (Credit) [Abstract] Disclosure Employee Benefit Plans Components Of Net Benefit Cost Credit [Abstract] Disclosure - EMPLOYEE BENEFIT PLANS - Components of Net Benefit Cost (Credit) [Abstract] Disclosure Fair Value Measurements Additional Information [Abstract] Disclosure Fair Value Measurements Additional Information [Abstract] Disclosure Fair Value Measurements Additional Information [Abstract] Disclosure - FAIR VALUE MEASUREMENTS - Categorization of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis [Abstract] Disclosure Fair Value Measurements Categorization Of Investments And Certain Other Assets And Liabilities Measured At Fair Value On Recurring Basis [Abstract] Disclosure - FAIR VALUE MEASUREMENTS - Categorization of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis [Abstract] Disclosure - FAIR VALUE MEASUREMENTS - Fair Value of Certain Investments Based on NAV [Abstract] Disclosure Fair Value Measurements Fair Value Of Certain Investments Based On Nav [Abstract] Disclosure - FAIR VALUE MEASUREMENTS - Fair Value of Certain Investments Based on NAV [Abstract] Disclosure - FAIR VALUE MEASUREMENTS - Summary of Changes in Fair Value of Company's Level 3 Assets [Abstract] Disclosure Fair Value Measurements Summary Of Changes In Fair Value Of Companys Level 3 Assets [Abstract] Disclosure - FAIR VALUE MEASUREMENTS - Summary of Changes in Fair Value of Company's Level 3 Assets [Abstract] Disclosure Goodwill And Other Intangible Assets Additional Information [Abstract] Disclosure Goodwill And Other Intangible Assets Additional Information [Abstract] Disclosure Goodwill And Other Intangible Assets Additional Information [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Changes in Carrying Amount of Goodwill [Abstract] Disclosure Goodwill And Other Intangible Assets Changes In Carrying Amount Of Goodwill [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Changes in Carrying Amount of Goodwill [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Components of Goodwill and Other Intangible Assets [Abstract] Disclosure Goodwill And Other Intangible Assets Components Of Goodwill And Other Intangible Assets [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Components of Goodwill and Other Intangible Assets [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Estimated Future Amortization Expense [Abstract] Disclosure Goodwill And Other Intangible Assets Estimated Future Amortization Expense [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Estimated Future Amortization Expense [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Gross Cost and Accumulated Amortization of Other Intangible Assets [Abstract] Disclosure Goodwill And Other Intangible Assets Gross Cost And Accumulated Amortization Of Other Intangible Assets [Abstract] Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Gross Cost and Accumulated Amortization of Other Intangible Assets [Abstract] Disclosure - INCENTIVE PLANS - Additional Information [Abstract] Disclosure Incentive Plans Additional Information [Abstract] Disclosure - INCENTIVE PLANS - Additional Information [Abstract] Disclosure - INCENTIVE PLANS - Schedule of Activity Relating to RSUs and DSUs [Abstract] Disclosure Incentive Plans Schedule Of Activity Relating To R S Us And D S Us [Abstract] Disclosure - INCENTIVE PLANS - Schedule of Activity Relating to RSUs and DSUs [Abstract] Disclosure - INCENTIVE PLANS - Summary of Activity Related to Shares of Restricted Class A Common Stock [Abstract] Disclosure Incentive Plans Summary Of Activity Related To Shares Of Restricted Classa Common Stock [Abstract] Disclosure - INCENTIVE PLANS - Summary of Activity Related to Shares of Restricted Class A Common Stock [Abstract] Disclosure - INCENTIVE PLANS - Summary of Fund Interests and Other Similar Deferred Compensation Arrangements [Abstract] Disclosure Incentive Plans Summary Of Fund Interests And Other Similar Deferred Compensation Arrangements [Abstract] Disclosure - INCENTIVE PLANS - Summary of Fund Interests and Other Similar Deferred Compensation Arrangements [Abstract] Disclosure - INCENTIVE PLANS - Summary of Impact of Fund Interests and Other Similar Deferred Compensation [Abstract] Disclosure Incentive Plans Summary Of Impact Of Fund Interests And Other Similar Deferred Compensation [Abstract] Disclosure - INCENTIVE PLANS - Summary of Impact of Fund Interests and Other Similar Deferred Compensation [Abstract] Disclosure - INCENTIVE PLANS - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense [Abstract] Disclosure Incentive Plans Summary Of Impact Of Share Based Incentive Plans On Compensation And Benefits Expense [Abstract] Disclosure - INCENTIVE PLANS - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Investments Additional Information [Abstract] Disclosure Investments Additional Information [Abstract] Disclosure Investments Additional Information [Abstract] Disclosure - INVESTMENTS - Company's Investments and Securities Sold, Not Yet Purchased [Abstract] Disclosure Investments Companys Investments And Securities Sold Not Yet Purchased [Abstract] Disclosure - INVESTMENTS - Company's Investments and Securities Sold, Not Yet Purchased [Abstract] Disclosure - INVESTMENTS - Schedule of Trading Securities Gross Unrealized Investment Gains and Losses [Abstract] Disclosure I N V E S T M E N T S Schedule Of Trading Securities Gross Unrealized Investment Gains And Losses [Abstract] Disclosure - INVESTMENTS - Schedule of Trading Securities Gross Unrealized Investment Gains and Losses [Abstract] Disclosure - MEMBERS' EQUITY - Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Disclosure Members Equity Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract] Disclosure - MEMBERS' EQUITY - Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Disclosure - MEMBERS' EQUITY - Additional Information [Abstract] Disclosure Members Equity Additional Information [Abstract] Disclosure - MEMBERS' EQUITY - Additional Information [Abstract] Disclosure - MEMBERS' EQUITY - Lazard Group Distributed Amounts to LAZ-MD Holdings and Subsidiaries of Lazard Ltd [Abstract] Disclosure Members Equity Lazard Group Distributed Amounts To Laz Md Holdings And Subsidiaries Of Lazard Ltd [Abstract] Disclosure - MEMBERS' EQUITY - Lazard Group Distributed Amounts to LAZ-MD Holdings and Subsidiaries of Lazard Ltd [Abstract] Disclosure - MEMBERS' EQUITY - Net Income Attributable to Noncontrolling Interests [Abstract] Disclosure Members Equity Net Income Attributable To Noncontrolling Interests [Abstract] Disclosure - MEMBERS' EQUITY - Net Income Attributable to Noncontrolling Interests [Abstract] Disclosure Of Compensation Related Costs Share Based Payments [Text Block] INCENTIVE PLANS Disclosure - ORGANIZATION AND BASIS OF PRESENTATION - Additional Information [Abstract] Disclosure Organization And Basis Of Presentation Additional Information [Abstract] Disclosure - ORGANIZATION AND BASIS OF PRESENTATION - Additional Information [Abstract] Disclosure - PROPERTY-NET - Summary of Property-Net [Abstract] Disclosure Property Net Summary Of Property Net [Abstract] Disclosure - PROPERTY-NET - Summary of Property-Net [Abstract] Disclosure Receivables Additional Information [Abstract] Disclosure Receivables Additional Information [Abstract] Disclosure Receivables Additional Information [Abstract] Disclosure - REGULATORY AUTHORITIES - Additional Information [Abstract] Disclosure Regulatory Authorities Additional Information [Abstract] Disclosure - REGULATORY AUTHORITIES - Additional Information [Abstract] Disclosure Related Parties Additional Information [Abstract] Disclosure Related Parties Additional Information [Abstract] Disclosure Related Parties Additional Information [Abstract] Disclosure - RELATED PARTIES - Schedule of Amounts Receivable from and Payable to Related Parties [Abstract] Disclosure Related Parties Schedule Of Amounts Receivable From And Payable To Related Parties [Abstract] Disclosure - RELATED PARTIES - Schedule of Amounts Receivable from and Payable to Related Parties [Abstract] Disclosure - SEGMENT INFORMATION - Schedule of Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets [Abstract] Disclosure Segment Information Schedule Of Segments Contribution With Respect To Net Revenue Operating Expenses Operating Income Loss And Total Assets [Abstract] Disclosure - SEGMENT INFORMATION - Schedule of Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets [Abstract] Disclosure - SENIOR AND SUBORDINATED DEBT - Additional Information [Abstract] Disclosure Senior And Subordinated Debt Additional Information [Abstract] Disclosure - SENIOR AND SUBORDINATED DEBT - Additional Information [Abstract] Disclosure - SENIOR AND SUBORDINATED DEBT - Senior Debt [Abstract] Disclosure Senior And Subordinated Debt Senior Debt [Abstract] Disclosure - SENIOR AND SUBORDINATED DEBT - Senior Debt [Abstract] Disclosure Subsequent Event Additional Information [Abstract] Disclosure Subsequent Event Additional Information [Abstract] Disclosure Subsequent Event Additional Information [Abstract] Distributions to members. Distributions To Members Distributions to members Distribution to members and noncontrolling interests, net. Distribution To Members And Noncontrolling Interests Net Distributions to members and noncontrolling interests, net Dividend participation rights. Dividend Participation Rights Dividend participation rights