Entity Central Index Key Document and entity information abstract. Document And Entity Information [Abstract] Document Information [Table] Document Information [Table] Consolidated Entities Consolidated Entities [Axis] Consolidated Entities Consolidated Entities [Domain] Subsidiaries of Lazard Ltd [Member] Subsidiaries [Member] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Membership Interests, Shares Outstanding Common Unit Outstanding Represents deposits with banks and investments with a maturity of less than 90 days. Receivables from customers related to collateralized lending activities, loans granted by bank to third party clients, managing directors, employees in the ordinary course of business, receivables from brokers-dealers and clearing organizations relating to unsettled securities transactions and receivables from related parties. Deposits and other customer payables principally related to customer-related interest-bearing time and demand deposits, short-term inter-bank borrowing with registered banks, amounts due on collateralized borrowing activities and other related party payables. Statement Of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Deposits with banks and short-term investments Deposits With Banks And Short Term Investments Cash deposited with clearing organizations and other segregated cash Cash And Securities Segregated Under Federal And Other Regulations Receivables (net of allowance for doubtful accounts of $38,505 and $23,692 at March 31, 2018 and December 31, 2017, respectively): Accounts Receivable Net [Abstract] Fees Accrued Fees And Other Revenue Receivable Customers and other Receivables From Customers And Other Lazard Ltd subsidiaries Due From Related Parties Total receivables, net Accounts Receivable Net Investments Investments Property (net of accumulated amortization and depreciation of $329,031 and $317,816 at March 31, 2018 and December 31, 2017, respectively) Property Plant And Equipment Net Goodwill and other intangible assets (net of accumulated amortization of $61,819 and $61,202 at March 31, 2018 and December 31, 2017, respectively) Intangible Assets Net Including Goodwill Deferred tax assets Deferred Income Tax Assets Net Other assets Other Assets Total Assets Assets Allowance for doubtful accounts receivables Allowance For Doubtful Accounts Receivable Property, accumulated amortization and depreciation Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Other intangible assets, accumulated amortization Finite Lived Intangible Assets Accumulated Amortization Liabilities: Liabilities [Abstract] Deposits and other customer payables Deposits And Other Customer Payables Accrued compensation and benefits Employee Related Liabilities Current And Noncurrent Senior debt Long Term Debt Payable to Lazard Ltd subsidiaries Due To Related Parties Current And Noncurrent Deferred tax liabilities Deferred Income Tax Liabilities Net Other liabilities Other Liabilities Total Liabilities Liabilities Commitments and contingencies Commitments And Contingencies MEMBERS’ EQUITY Members Equity [Abstract] Members' equity (net of 8,521,661 and 9,907,479 shares of Lazard Ltd Class A common stock, at a cost of $383,813 and $411,560 at March 31, 2018 and December 31, 2017, respectively) Members Capital Accumulated other comprehensive loss, net of tax Accumulated Other Comprehensive Income Loss Net Of Tax Total Lazard Group LLC Members' Equity Members Equity Noncontrolling interests Members Equity Attributable To Noncontrolling Interest Total Members’ Equity Limited Liability Company Llc Members Equity Including Portion Attributable To Noncontrolling Interest Total Liabilities and Members’ Equity Liabilities And Stockholders Equity 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. 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. Lazard Ltd common stock, shares Common Stock Held In Parent Company Shares Lazard Ltd common stock, cost Common Stock Held In Parent Company Value Includes advisory fees earned for providing advice and analysis related to corporate mergers, acquisitions, divestures, and funding. Also includes restructuring advisory fees earned involving a client or a client's portfolio company in bankruptcy, in financial distress and/or is significantly over leveraged. Consisting of fees paid for outsourced services and asset management related expenses for mutual fund servicing, fund administration by third parties. In addition, custodial, clearing and settlement costs. Amount of amortization and other acquisition related costs. Income Statement [Abstract] REVENUE Revenues Net Of Interest Expense [Abstract] Investment banking and other advisory fees Investment Banking And Other Advisory Fees Asset management fees Asset Management Fees1 Interest income Interest Income Operating Other Other Income Total revenue Revenues Interest expense Interest Expense Net revenue Revenues Net Of Interest Expense OPERATING EXPENSES Costs And Expenses [Abstract] Compensation and benefits Labor And Related Expense Occupancy and equipment Occupancy Net Marketing and business development Business Development Technology and information services Information Technology And Data Processing Professional services Professional Fees Fund administration and outsourced services Fund Administration And Outsourced Services Amortization and other acquisition-related costs Amortization And Other Acquisition Related Costs Other Other Expenses Total operating expenses Costs And Expenses OPERATING INCOME Operating Income Loss Provision for income taxes Income Tax Expense Benefit NET INCOME Profit Loss LESS - NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Net Income Loss Attributable To Noncontrolling Interest NET INCOME ATTRIBUTABLE TO LAZARD GROUP LLC Net Income Loss Statement Of Income And Comprehensive Income [Abstract] NET INCOME OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX: Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Currency translation adjustments Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax Employee benefit plans: Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease [Abstract] Actuarial loss (net of tax benefit of $1,342 and $261 for the three months ended March 31, 2018 and 2017, respectively) Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax Adjustment for items reclassified to earnings (net of tax expense of $216 and $276 for the three months ended March 31, 2018 and 2017, respectively) Other Comprehensive Income Loss Reclassification Adjustment From A O C I Pension And Other Postretirement Benefit Plans Net Of Tax OTHER COMPREHENSIVE INCOME, NET OF TAX Other Comprehensive Income Loss Net Of Tax COMPREHENSIVE INCOME Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD GROUP LLC Comprehensive Income Net Of Tax Tax benefit on actuarial loss, employee benefit plans Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax Tax expense, adjustment for items reclassified to earnings, employee benefit plans Other Comprehensive Income Loss Reclassification Adjustment From A O C I Pension And Other Postretirement Benefit Plans Tax Amortization of deferred expenses and share- based compensation. 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. Proceeds relating to customer deposits. The cash inflow from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy. Payments relating to customer deposits. The cash outflow from the settlement of share-based incentive compensation. The cash outflow from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy. Proceeds from financing activities. Payments for financing activities. Statement Of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided By Used In Operating Activities Continuing Operations [Abstract] Adjustments to reconcile net income to net cash provided by (used in) operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Depreciation and amortization of property Depreciation Depletion And Amortization Amortization of deferred expenses and share-based incentive compensation Amortization Of Deferred Expenses And Sharebased Incentive Compensation Amortization and other acquisition-related costs Deferred tax provision Deferred Income Tax Expense Benefit (Increase) decrease in operating assets: Increase Decrease In Operating Assets [Abstract] Receivables-net Increase Decrease In Receivables Investments Increase Decrease In Financial Instruments Used In Operating Activities Other assets Increase Decrease In Other Operating Assets Increase (decrease) in operating liabilities: Increase Decrease In Operating Liabilities [Abstract] Accrued compensation and benefits and other liabilities Increase Decrease In Accrued Compensation And Benefits And Other Liabilities Net cash (used in) provided by operating activities Net Cash Provided By Used In Operating Activities Continuing Operations CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided By Used In Investing Activities Continuing Operations [Abstract] Additions to property Payments To Acquire Property Plant And Equipment Disposals of property Proceeds From Sale Of Property Plant And Equipment Net cash used in investing activities Net Cash Provided By Used In Investing Activities Continuing Operations CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided By Used In Financing Activities Continuing Operations [Abstract] Proceeds from: Proceeds From Financing Activities [Abstract] Customer deposits Proceeds From Customer Deposits Other financing activities Proceeds From Other Financing Activities Payments for: Payments For Financing Activities [Abstract] Capital lease obligations Repayments Of Long Term Capital Lease Obligations Customer deposits Payments Relating To Customer Deposits Distributions to noncontrolling interests Payments To Minority Shareholders Purchase of Lazard Ltd Class A common stock Payments For Repurchase Of Common Stock Distributions to members Payments Of Distributions To Affiliates Settlement of vested share-based incentive compensation Settlement Of Share Based Incentive Compensation Other financing activities Payments For Other Financing Activities Net cash used in financing activities Net Cash Provided By Used In Financing Activities Continuing Operations EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS AND RESTRICTED CASH Effect Of Exchange Rate On Cash And Cash Equivalents Continuing Operations NET DECREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CASH AND CASH EQUIVALENTS AND RESTRICTED CASH—January 1 Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CASH AND CASH EQUIVALENTS AND RESTRICTED CASH—March 31 Reconciliation of cash and cash equivalents and restricted cash within the condensed consolidated statements of financial condition. RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH WITHIN THE CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION: Reconciliation Of Cash And Cash Equivalents And Restricted Cash Within Condensed Consolidated Statements Of Financial Condition [Abstract] TOTAL CASH AND CASH EQUIVALENTS AND RESTRICTED CASH Amortization of share-based incentive compensation. Total distributions to members and non-controlling interest holders. Purchase of parent company's common stock. Value of shares delivered from treasury stock during the period as a result of an equity-based compensation plan and related tax benefit (expense). Value of Parent Company stock issued or issuable in connection with acquisitions and subsidiary merger and related amortization. Amount of ownership interest in a limited liability company (LLC), including portions attributable to both the parent and noncontrolling interests, after the cumulative effect adjustment of a new accounting principle applied in the period of adoption. Business acquisitions and related equity transactions. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Members equity. Members' Equity [Member] Members Equity [Member] Accumulated Other Comprehensive Income (Loss), Net of Tax [Member] Accumulated Other Comprehensive Income [Member] Total Lazard Group LLC Members' Equity [Member] Parent [Member] Noncontrolling Interests [Member] Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Balance Adjustment for the cumulative effect on prior years from the adoption of new accounting guidance related to share-based incentive compensation Cumulative Effect Of New Accounting Principle In Period Of Adoption Balance, as adjusted Limited Liability Company Llc Members Equity Including Portion Attributable To Noncontrolling Interest Adjusted Balance1 Comprehensive income: Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract] Net income Other comprehensive income - net of tax Amortization of share-based incentive compensation Amortization Of Share Based Incentive Compensation Distributions to members and noncontrolling interests, net Distributions To Members And Non Controlling Interest Holders Purchase of Lazard Ltd Class A common stock Purchase Of Parent Company Common Stock Delivery of Lazard Ltd Class A common stock in connection with share-based incentive compensation Delivery Of Shares From Treasury Stock During The Period Net Of Tax On Share Based Compensation Business acquisitions and related equity transactions: Business Acquisitions And Related Equity Transactions [Abstract] Lazard Ltd Class A common stock issuable (including related amortization) Parent Company Stock Issued Issuable During Period Value Business Acquisitions Mergers And Amortization Other Partners Capital Other Balance Organization Consolidation And Presentation Of Financial Statements [Abstract] Organization and Basis of Presentation Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] New Accounting Pronouncements And Changes In Accounting Principles [Abstract] Recent Accounting Developments New Accounting Pronouncements And Changes In Accounting Principles [Text Block] The entire disclosure for the new revenue recognition guidance. Revenue Recognition [Abstract] Revenue Recognition Revenue Recognition [Text Block] Receivables [Abstract] Receivables Loans Notes Trade And Other Receivables Disclosure [Text Block] Investments Schedule [Abstract] Investments Investment [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Measurement Inputs Disclosure [Text Block] Derivative Instruments And Hedging Activities Disclosure [Abstract] Derivatives Derivative Instruments And Hedging Activities Disclosure [Text Block] Property, Plant and Equipment [Abstract] Property Property Plant And Equipment Disclosure [Text Block] Goodwill And Intangible Assets Disclosure [Abstract] Goodwill and Other Intangible Assets Goodwill And Intangible Assets Disclosure [Text Block] Debt Disclosure [Abstract] Senior Debt Debt Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Equity [Abstract] Members' Equity Members Equity Notes Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Incentive Plans Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Compensation And Retirement Disclosure [Abstract] Employee Benefit Plans Pension And Other Postretirement Benefits Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Related Party Transactions [Abstract] Related Parties Related Party Transactions Disclosure [Text Block] The entire disclosure for regulatory requirements regarding minimum capital requirements and amounts in excess of those requirements. Regulatory Capital Requirements [Abstract] Regulatory Authorities Regulatory Authorities [Text Block] Segment Reporting [Abstract] Segment Information Segment Reporting Disclosure [Text Block] Disclosure of accounting policy for the nature of an entity's business, major products or services, principal markets including location and relative importance of its operation in each reporting segment and basis of determination. Organization Organization Policy [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Recent Accounting Developments New Accounting Pronouncements Policy Policy [Text Block] Revenue Recognition Policy Revenue Recognition Policy [Text Block] Derivative Instruments Derivatives Policy [Text Block] Representation of Performance Obligations Relate to Nature, Amount, Timing and Uncertainty of Revenue and Cash Flows Revenue Recognition Multiple Deliverable Arrangements Table [Text Block] Tabular disclosure of activity in the allowance for doubtful accounts. Schedule of Activity in Allowance for Doubtful Accounts Schedule Of Allowance For Doubtful Accounts Table [Text Block] Tabular disclosure of Investments including debt equity securities funds and interest bearing deposits as well as investments accounted for under equity method and securities sold not yet purchased. Company's Investments and Securities Sold, Not Yet Purchased Investments Including Debt Equity Securities Funds And Interest Bearing Deposits As Well As Investments Accounted For Under Equity Method And Securities Sold Not Yet Purchased Table [Text Block] Schedule of Trading Securities Net Unrealized Investment Gains and Losses Unrealized Gain Loss On Investments Table [Text Block] Fair Value Measurement Policy Fair Value Measurement Policy Policy [Text Block] Schedule of Classification of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis and Investments Measured at NAV Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis Table [Text Block] Tabular disclosure of changes in the fair value of level 3 assets and contingent consideration liabilities. Summary of Changes in Fair Value of Company's Level 3 Assets and Liabilities Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Table [Text Block] Fair Value of Certain Investments Based on NAV Fair Value Investments Entities That Calculate Net Asset Value Per Share Table [Text Block] Fair Values of Derivatives Reported on Condensed Consolidated Statements of Financial Condition Schedule Of Derivative Instruments In Statement Of Financial Position Fair Value [Text Block] Net Gains (Losses) with Respect to Derivative Instruments Not Designated as Hedging Instruments Schedule Of Derivative Instruments Gain Loss In Statement Of Financial Performance [Text Block]