Document And Entity Information [Abstract] Document And Entity Information [Abstract] Statement [Table] Statement [Line Items] Document Type Amendment Flag Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Condensed Consolidated Statements Of Financial Condition [Abstract] ASSETS Cash and Cash Equivalents, at Carrying Value CASH AND CASH EQUIVALENTS-March 31 CASH AND CASH EQUIVALENTS-January 1 Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value, Total Interest-bearing Deposits in Banks and Other Financial Institutions Banks Deposits with banks Cash and Securities Segregated under Federal and Other Regulations Cash deposited with clearing organizations and other segregated cash Cash and Securities Segregated under Federal and Other Regulations, Total Receivables Net [Abstract] Receivables Net [Abstract] Receivables (net of allowance for doubtful accounts of $21,172 and $19,450 at March 31, 2012 and December 31, 2011, respectively): Accrued Fees and Other Revenue Receivable Fees Receivables from customers related to collateralized lending activities, loans granted by bank to third party clients, and managing directors and, employees in the ordinary course of business, and receivables from brokers-dealers and clearing organizations relating to unsettled securities transactions. Receivables From Customers And Other Customers and other Due from Related Parties Related parties Due from Related Parties, Total Represents receivables from fees, customer and other and related parties, net of allowance for doubtful accounts. Receivables Net, Total receivables, net Total receivables, net Investments, Total Investments Total investments Property, Plant and Equipment, Net Property, Plant and Equipment, Net, Ending Balance Property, Plant and Equipment, Net, Beginning Balance Property (net of accumulated amortization and depreciation of $265,223 and $266,673 at March 31, 2012 and December 31, 2011, respectively) Property, Plant and Equipment, Net, Total Sum of the carrying amounts of all goodwill and intangible assets as of the balance sheet date, net of accumulated amortization and impairment charges. Goodwill And Intangible Assets Net Goodwill and other intangible assets (net of accumulated amortization of $28,040 and $26,922 at March 31, 2012 and December 31, 2011, respectively) Other Assets Other assets Other Assets, Total Assets, total Total assets Liabilities: 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 Employee-related Liabilities Accrued compensation and benefits Employee-related Liabilities, Total Senior Notes Senior debt Senior Notes, Total Capital lease obligations Capital Lease Obligations, Total Due to Related Parties Related party payables Due to Related Parties, Total Other liabilities Other Liabilities, Total Liabilities Total liabilities Commitments and Contingencies, Total Commitments and contingencies Partners' Capital [Abstract] MEMBERS' EQUITY General Partners' Capital Account Members' equity (net of 1,108,723 and 2,174,573 shares of Lazard Ltd Class A common stock, at a cost of $34,687, and $72,410 at March 31, 2012 and December 31, 2011, respectively) common stock, at cost of $141,593 and $227,950 at September 30, 2011 and December 31, 2010, respectively) Accumulated Other Comprehensive Income (Loss), Net of Taxes Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance Accumulated other comprehensive loss, net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax, Total Partners' Capital Partners' Capital, Ending Balance Partners' Capital, Beginning Balance Total Lazard Group members' equity Stockholders' Equity Attributable to Noncontrolling Interest Stockholders' Equity Attributable to Noncontrolling Interest, Ending Balance Stockholders' Equity Attributable to Noncontrolling Interest, Beginning Balance Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest, Total Partners' Capital, Including Portion Attributable to Noncontrolling Interest Balance Balance Total members' equity Liabilities and Equity Total liabilities and members' equity Total liabilities and members' equity Allowance for Doubtful Accounts Receivable, Current Allowance for Doubtful Accounts Receivable, Current, Ending Balance Allowance for Doubtful Accounts Receivable, Current, Beginning Balance Receivables, allowance for doubtful accounts Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Property, accumulated amortization and depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total Finite-Lived Intangible Assets, Accumulated Amortization Goodwill and other intangible assets, accumulated amortization Accumulated amortization 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 Class A common stock, shares Lazard Ltd Class A 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 Class A common stock, at cost Lazard Ltd Class A common stock, cost Condensed Consolidated Statements Of Operations [Abstract] REVENUE 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. Investment banking and other advisory fees Asset Management Fees Money management fees Asset Management Fees, Total Interest Income, Operating Interest income Other Income Other Other Income, Total Revenues Total revenue The cost of borrowed funds accounted for as interest that was charged against earnings during the period and aggregate amount of interest expense on all deposits. Interest Expense And Interest Expense Deposits Interest expense Revenue, net of interest expense. Net Revenue Net revenue Costs and Expenses OPERATING EXPENSES Labor and Related Expense Compensation and benefits Labor and Related Expense, Total Occupancy, Net Occupancy and equipment Captures expenses relating to business development such as travel and business meals, advertising, marketing and public relations, as well as fees paid to third parties retained by Lazard to introduce business or gather assets under management. Marketing And Business Development Expense Marketing and business development Captures expenses relating to investments in technology including software development and maintenance, acquisition of hardware through purchase or lease, and expenses relating to voice, network data and market data. Also includes consulting fees related to technology. Technology And Information Services Expense Technology and information services Fees relating to legal, audit, consulting, advisory and compliance services. Professional services 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. Fund Administration And Outsourced Services Fund administration and outsourced services Amortization of Intangible Assets Amortization of intangible assets related to acquisitions Amortization of Intangible Assets, Total Other Expenses Other Other Expenses, Total Costs and Expensesa Total operating expenses Operating Income (Loss) OPERATING INCOME Income Tax Expense (Benefit) Provision for income taxes Income Tax Expense (Benefit), Total Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income NET INCOME NET INCOME Net Income (Loss) Attributable to Noncontrolling Interest LESS - NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Net Income (Loss) Attributable to Noncontrolling Interest, Total Net Income (Loss) Attributable to Parent NET INCOME ATTRIBUTABLE TO LAZARD GROUP Condensed Consolidated Statements Of Comprehensive Income [Abstract] OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX: Other comprehensive income (loss) - net of tax: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Currency translation adjustments Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Amortization of interest rate hedge Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Total Amortization of interest rate hedge Employee benefit plans: Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized (Gain) Loss Arising During Period, Net of Tax Net actuarial gain (loss) Net actuarial loss (net of tax benefit of $1,282 and $1,935 for the three months ended March 31, 2012 and 2011, respectively) Includes the adjustment out of other comprehensive income for (1) actuarial gains (losses), and (2) prior service costs, both recognized as a component of net period benefit cost during the period, after tax. Other Comprehensive Income Net Actuarial Gains Losses And Prior Service Cost Arising During Period Net Of Tax Adjustment for items reclassified to earnings (net of tax expense of $297 and $255 for the three months ended March 31, 2012 and 2011, respectively) Adjustments for items reclassified to earnings Adjustment for items reclassified to earnings (net of tax expense of $297 and $255 for the three months ended March 31, 2012 and 2011, respectively) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent OTHER COMPREHENSIVE INCOME, NET OF TAX Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest, Total Comprehensive Income (Loss), Net of Tax, Attributable to Parent COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD GROUP Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax Net actuarial loss, tax benefit Other comprehensive income net actuarial gains losses and prior service cost arising during period tax. Other Comprehensive Income Net Actuarial Gains Losses and Prior Service Cost Arising During Period Tax Adjustment for items reclassified to earnings tax expense Condensed Consolidated Statements Of Cash Flows [Abstract] CASH FLOW FROM OPERATING ACTIVITIES: CASH FLOWS FROM OPERATING ACTIVITIES: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Noncash items included in net income: 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 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 Gain loss on sale of intercompany receivable. Gain Loss on Sale of Intercompany Receivable Loss on sale of intercompany receivable Increase (Decrease) in Operating Assets [Abstract] (Increase) decrease in operating assets: Proceeds from (Payments for) in Interest-bearing Deposits in Banks Deposits with banks Deposits with banks The net change during the reporting period in the amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances, and cash and securities segregated in compliance with regulations (such as cash deposited in a special reserve account for the exclusive benefit of customers pursuant). Increase Decrease In Cash And Securities Segregated Under Federal And Other Regulations Cash deposited with clearing organizations and other segregated cash Cash deposited with clearing organizations and other segregated cash Increase (Decrease) in Receivables Receivables-net Receivables - net Increase (Decrease) in Receivables, Total Increase (Decrease) in Financial Instruments Used in Operating Activities Investments Investments Increase (Decrease) in Financial Instruments Used in Operating Activities, Total Increase (Decrease) in Other Operating Assets Other assets Other assets Increase (Decrease) in Other Operating Assets, Total Increase (Decrease) in Operating Liabilities [Abstract] Increase (decrease) in operating liabilities: Increase (Decrease) In Deposits And Other Customer Payables. Increase Decrease In Deposits And Other Customer Payables Deposits and other payables 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 Net Cash Provided by (Used in) Operating Activities Net cash provided by operating activities Net cash used in operating activities CASH FLOWS FROM INVESTING ACTIVITIES: Payments to Acquire Property, Plant, and Equipment Additions to property Additions to property Payments to Acquire Property, Plant, and Equipment, Total Proceeds from Sale of Property, Plant, and Equipment Disposals of property Proceeds from Sale of Property, Plant, and Equipment, Total Net Cash Provided by (Used in) Investing Activities Net cash provided by (used in) investing activities Net cash used in investing activities Proceeds From Financing Activities [Abstract] Proceeds From Financing Activities [Abstract] Proceeds from: Proceeds from Noncontrolling Interests Contributions from noncontrolling interests Proceeds from sale of intercompany receivable. Proceeds from Sale of Intercompany Receivable Sale of intercompany receivable The cash inflow from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy. Proceeds From Other Financing Activities Other financing activities Payments For Financing Activities [Abstract] Payments For Financing Activities [Abstract] Payments for: Repayments of Long-term Capital Lease Obligations Capital lease obligations Capital lease obligations The cash outflow to return capital to noncontrolled interest, which generally occurs when noncontrolling shareholders reduce their ownership stake (in a subsidiary of the entity). This element includes dividends paid and other distributions to noncontrolling shareholders. Payments To Minority Shareholders Including Dividends Distributions to noncontrolling interests Distributions to noncontrolling interests 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 from members of LAZ-MD Holdings Purchase of Parent Company's Common Stock. Purchase Of Parent Company Common Stock Purchase of Lazard Ltd Class A common stock Distributions to Members Distributions To Members Distributions to members The cash outflow from the settlement of share-based incentive compensation. Settlement Of Share Based Incentive Compensation Settlement of vested share-based incentive compensation Settlement of vested 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. Payments For Other Financing Activities Other financing activities Other financing activities Net Cash Provided by (Used in) Financing Activities Net cash used in financing activities Net cash used in financing activities Effect of Exchange Rate on Cash and Cash Equivalents EFFECT OF EXCHANGE RATE CHANGES ON CASH EFFECT OF EXCHANGE RATE CHANGES ON CASH Cash and Cash Equivalents, Period Increase (Decrease) NET DECREASE IN CASH AND CASH EQUIVALENTS NET DECREASE IN CASH AND CASH EQUIVALENTS Condensed Consolidated Statements Of Changes In Members' Equity [Abstract] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Members' Equity [Member] Accumulated Other Comprehensive Income [Member] Accumulated Other Comprehensive Income (Loss), Net Of Tax [Member] Noncontrolling Interest [Member] Noncontrolling Interests [Member] Comprehensive income (loss): Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Amortization of share-based incentive compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total Payment of dividend or other distributions to controlling and noncontrolling interest holders. Distribution to Members and Noncontrolling Interests, Net Distributions to members and noncontrolling interest, net Distribution to members and noncontrolling interests, net Value of parent company common stock for 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 Delivery Of Parent COmpany COmmon Stock Share Based Compensation And Related Tax Expense Delivery Of Parent COmpany COmmon Stock Share Based Compensation And Related Tax Expense Delivery of Lazard Ltd Class A common stock in connection with share-based incentive compensation and related tax expense of $972 Delivery of Lazard Ltd Class A common stock in connection with share-based incetive compesation and related tax expense Repurchase of common membership interests during the period. Common Membership Interest Repurchased During Period Value Repurchase of common membership interests from LAZ-MD Holdings Value of Parent Company stock issued or issuable in connection with acquisitions and subsidiary merger and related amortization. Parent Company Stock Issued Issuable During Period Value Business Acquisitions Mergers And Amortization Lazard Ltd Class A common stock issuable (including related amortization) Partners Capital Other Other Other Common membership interest. Common Membership Interest Common membership interests Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Share-based incentive compensation, tax expense from compensation Company's Class A common stock. Common Stock Class A Class A common stock issued Organization And Basis Of Presentation [Abstract] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization And Basis Of Presentation Recent Accounting Developments [Abstract] Basis of Presentation and Significant Accounting Policies [Text Block] Recent Accounting Developments Receivables-Net [Abstract] Disclosure related to receivables from fees, customer and other and related parties, net of allowance for doubtful accounts. Receivables Net [Text Block] Receivables-Net Investments [Abstract] Investment [Text Block] Investments Fair Value Measurements [Abstract] Fair Value, Measurement Inputs, Disclosure [Table Text Block] Fair Value Measurements Derivatives [Abstract] Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivatives Business Acquisitions [Abstract] Business Combination Disclosure [Text Block] Business Acquisitions Goodwill And Other Intangible Assets [Abstract] Goodwill and Intangible Assets Disclosure [Text Block] Goodwill And Other Intangible Assets Senior Debt [Abstract] Debt Disclosure [Text Block] Senior Debt Commitments And Contingencies [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments And Contingencies Members' equity. Members' Equity [Abstract] Disclosures relating to activities of common membership interests and certain activities of the Parent Company. Members Equity Note Disclosure [Text Block] Members' Equity Incentive Plans [Abstract] Disclosure of share based compensation arrangements by share based payment award and other incentive awards. Disclosure of Share Based Compensation Arrangements by Share Based Payment Award and Other Incentive Awards [Text Block] Incentive Plans Employee Benefit Plans [Abstract] Pension and Other Postretirement Benefits Disclosure [Text Block] Employee Benefit Plans Income Taxes [Abstract] Income Tax Disclosure [Text Block] Income Taxes Related Parties [Abstract] dup_1_Related Party Transaction, Due from (to) Related Party, Noncurrent, Total Related Party Transactions Disclosure [Text Block] Related Parties Regulatory Authorities [Abstract] Regulatory Capital Requirements under Banking Regulations [Text Block] Regulatory Authorities Segment Information [Abstract] Segment Reporting Disclosure [Text Block] Segment Information Parent Company [Member] Total Lazard Group Members' Equity [Member]