Document and Entity Information [Abstract] Document And Entity Information [Abstract] Statement [Table] Class of Stock [Axis] Class Of Stock [Domain] Class of Stock [Domain] Common Class A [Member] Class A Common Stock [Member] Common Class B [Member] Class B Common Stock [Member] Statement [Line Items] Document Type Amendment Flag Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Trading Symbol 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] Series A Preferred Stock [Member] Series A Preferred Stock [Member] Series B Preferred Stock [Member] Series B Preferred Stock [Member] ASSETS Cash and cash equivalents CASH AND CASH EQUIVALENTS-March 31 CASH AND CASH EQUIVALENTS-January 1 Cash and Cash Equivalents, at Carrying Value, Total Deposits with banks Banks 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): 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 Amounts receivables from related parties Due from Related Parties, Total Related parties Represents receivables from fees, customer and other and related parties, net of allowance for doubtful accounts. Receivables, Net Total receivables, net Investments, net Total Investments Total investments 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 $264,238 and $250,898 at March 31, 2011 and December 31, 2010, respectively) Property, Plant and Equipment, Net, Total Property (net of accumulated amortization and depreciation of $265,223 and $266,673 at March 31, 2012 and December 31, 2011, respectively) 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 $12,398 and $7,140 at September 30, 2010 and December 31, 2009, respectively) Goodwill and other intangible assets, Total 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, Total Total assets Total Assets Total assets LIABILITIES AND STOCKHOLDERS' EQUITY 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 Current And Noncurrent Accrued compensation and benefits Employee-related Liabilities, Total Senior debt Senior Debt, Outstanding Senior Notes, Total Capital lease obligations Capital Lease Obligations, Total Related party payables Amounts payables to related parties Due to Related Parties, Total Other liabilities Other Liabilities, Total Total liabilities Total liabilities Commitments and contingencies 2009 Commitments and contingencies Stockholders Equity [Abstract] STOCKHOLDERS' EQUITY Preferred Stock, Value, Issued Preferred Stock, Value, Issued, Ending Balance Preferred Stock, Value, Issued, Beginning Balance Preferred Stock, Value, Issued, Total Preferred stock Common Stock, Value [Abstract] Common Stock Value Abstract Common stock: Common Stock, Value, Issued Common Stock, Value, Issued, Ending Balance Common Stock, Value, Issued, Beginning Balance Common Stock, Value, Issued, Total Common stock Additional P-I-Cl Additional Paid in Capital, Ending Balance Additional Paid in Capital, Beginning Balance Additional paid-in-capital Additional Paid in Capital, Total Retained Earnings (Accumulated Deficit) Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit), Beginning Balance Retained Earnings (Accumulated Deficit), Total Retained earnings Accumulated other comprehensive income (loss), net of tax ELEMENT Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance Accumulated other comprehensive income (loss), net of tax Total Lazard Ltd AOCI Accumulated other comprehensive loss, net of tax Stockholders Equity Subtotal Before Common Stock Held By Subsidiary Stockholders Equity Subtotal Before Common Stock Held By Subsidiary Stockholders Equity Subtotal Before Common Stock Held By Subsidiary, Total Class A common stock held by a subsidiary, at cost (5,865,580 and 5,850,775 shares at September 30, 2010 and December 31, 2009, respectively) Class A common stock held by subsidiaries, at cost (3,267,892 and 3,492,017 shares at March 31, 2012 and December 31, 2011, respectively) Class A common stock held by a subsidiary, at cost (4,339,875 and 6,847,508 shares at June 30, 2011 and December 31, 2010, respectively) Class A common stock held by a subsidiary, at cost (4,339,875 and 6,847,508 shares at June 30, 2011 and December 31, 2010, respectively) Stockholders' Equity Attributable to Parent Stockholders' Equity Attributable to Parent, Ending Balance Stockholders' Equity Attributable to Parent, Beginning Balance Total Lazard Ltd stockholders' 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 Noncontrolling interests Total stockholders' equity Balance Balance Total stockholders' equity Total liabilities and stockholders' equity Total liabilities and stockholders' equity Allowance for Doubtful Accounts Receivable Estimated allowance for doubtful accounts Allowance for doubtful accounts receivable Property, accumulated amortization and depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total Other intangible assets (net of accumulated amortization) Other intangible assets, Accumulated Amortization Goodwill and other intangible assets, accumulated amortization Number of shares held by subsidiary, which are purchased for the purpose of granting the shares to senior employees as part of an employee stock option plan approved by the Entity's Board of Directors. Common stock held by subsidiary, shares Class A common stock held by a subsidiary, shares Common stock in exchange of RSUs Preferred stock, par value Par value of preferred stock Preferred stock, shares authorized Authorized shares of preferred stock Preferred stock, shares issued Preferred Stock, Shares Issued, Total Preferred stock, shares outstanding Preferred Stock, Shares Outstanding, Ending Balance Preferred Stock, Shares Outstanding, Beginning Balance Outstanding shares of preferred stock Convertible preferred stock Common stock, par value Common stock, shares authorized Common stock, shares issued Common Stock, Shares, Issued, Total Common stock, shares outstanding Common Stock, Shares, Outstanding, Ending Balance Common Stock, Shares, Outstanding, Beginning Balance 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 Money management fees Asset Management Fees, Total Interest income Other Income Other Income, Total Other Total revenue 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 OPERATING EXPENSES Compensation and benefits Labor and Related Expense, Total 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 Amortization of intangible assets related to acquisitions Amortization expense of intangible assets Amortization of Intangible Assets, Total Other Expenses Other Expenses, Total Other Total operating expenses Operating Expenses Total operating expenses OPERATING INCOME Operating Income (Loss) OPERATING INCOME Operating income (loss), as reported above Provision for income taxes Income tax provisions Provision for income taxes, total Net income (loss) 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 Noncontrolling Interests NET INCOME ATTRIBUTABLE TO LAZARD LTD NET INCOME ATTRIBUTABLE TO LAZARD LTD Net income (loss) attributable to Lazard Ltd Share Information Attributable To Parent Company CLass A Stockholders [Abstract] Share Information Attributable To Parent Company CLass Stockholders [Abstract] ATTRIBUTABLE TO LAZARD LTD CLASS A COMMON STOCKHOLDERS: WEIGHTED AVERAGE SHARES OF COMMON STOCK OUTSTANDING: Weighted Average Number of Shares Outstanding, Basic Weighted average number of shares of Class A common stock outstanding - basic Weighted Average Number of Shares Outstanding, Basic, Total Basic Weighted Average Number of Shares Outstanding, Diluted Weighted average number of shares of Class A common stock outstanding - diluted Weighted Average Number of Shares Outstanding, Diluted, Total Diluted Net Income Per Share Of Class A Common Stock [Abstract] NET INCOME PER SHARE OF COMMON STOCK: Earnings Per Share, Basic Net income attributable to Lazard Ltd per share of Class A common stock - Basic Earnings Per Share, Basic, Total Basic Earnings Per Share, Diluted Net income attributable to Lazard Ltd per share of Class A common stock - Diluted Earnings Per Share, Diluted, Total Diluted DIVIDENDS DECLARED PER SHARE OF COMMON STOCK Quarterly dividend declared per share Condensed Consolidated Statements Of Comprehensive Income [Abstract] OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX: Currency translation adjustments Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Amortization of interest rate hedge Other Comprehensive Income, Derivatives Qualifying as Hedges, Net of Tax, Total Employee benefit plans: Net actuarial gain (loss) Net actuarial 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 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 Other comprehensive income (loss), net of tax COMPREHENSIVE INCOME Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest, Total LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Comprehensive Income (Loss), Net of Tax, Attributable to Parent COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD LTD Tax benefit associated with actuary loss Tax benefit associated with actuary loss Tax expense associated with adjustment for item reclassified to earnings Tax expense associated with adjustment for item reclassified to earnings Condensed Consolidated Statements Of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Adjustments to reconcile net income to net cash provided by (used in) operating activities: Noncash items included in net income: 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 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 (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 Increase (Decrease) in Receivables, Total Increase Decrease In Financial Instruments Used In Operating Activities 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: Increase (Decrease) In Deposits And Other Customer Payables Increase Decrease In Deposits And Other Customer Payables Deposits and other 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 Net cash provided by operating activities Net cash used in operating activities Net cash provided by (used in) operating activities CASH FLOWS FROM INVESTING ACTIVITIES: Additions to property Additions to property Payments to Acquire Property, Plant, and Equipment, Total Disposals of property Proceeds from Sale of Property, Plant, and Equipment, Total Net cash provided by (used in) investing activities Net cash used in investing activities CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds From Financing Activities [Abstract] Proceeds From Financing Activities Abstract Proceeds from: Contributions from noncontrolling interests Contributions from noncontrolling interests 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 ProceedsFromOtherFinancingActivities 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 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 Payments For Repurchase Of Common Stock Purchase of Class A common stock Class A common stock dividends Class A common stock dividends The cash outflow from the settlement of share-based incentive compensation. Settlement Of 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 PaymentsForOtherFinancingActivities Other financing activities Net cash used in financing activities Net cash used in financing activities EFFECT OF EXCHANGE RATE CHANGES ON CASH Effect of Exchange Rate on Cash and Cash Equivalents, Total NET DECREASE IN CASH AND CASH EQUIVALENTS NET DECREASE IN CASH AND CASH EQUIVALENTS Condensed Consolidated Statements Of Changes In Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Common Stock [Member] Common Stock [Member] Additional Paid In Capital [Member] Additional Paid-In-Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income [Member] Accumulated Other Comprehensive Income (Loss), Net of Tax [Member] Common Stock Held by Subsidiary Common Stock Held By Subsidiary [Member] Class A Common Stock Held By A Subsidiary [Member] Parent [Member] Total Lazard Ltd Stockholders' Equity [Member] Noncontrolling Interest [Member] Noncontrolling Interests [Member] Shares, Issued Ending Balance (in shares) Ending balance (in shares) Beginning balance (in shares) Common membership interest activity in connection with secondary Offerings, Equity compensation Common stock, issued Comprehensive income: Comprehensive income (loss): Business Acquisitions [Abstract] Business Acquisitions Abstract Business Acquisitions [Abstract] Business acquisitions and related equity transactions: Value of stock issued or issuable in connection with acquisitions and subsidiary merger and related amortization. Stock Issued Issuable During Period Value Business Acquisitions Mergers And Amortization Class A common stock issued/issuable (including related amortization) Amortization of share-based incentive compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total Dividend equivalents. Dividend-equivalents Dividends, Common Stock Class A common stock dividends Dividends, Common Stock, Total Purchase of Class A common stock (in shares) Purchase of Class A common Stock Purchase of Class A common stock Purchase of Class A common stock Delivery of Class A common stock Value of stock issued during the period for share based compensation and related tax benefits Stock Issued During Period Value Share Based Compensation And Related Tax Benefits Delivery of Class A common stock in connection with share-based incentive compensation and related tax expense Shares of stock issued during the period for share based compensation and related tax benefits Stock Issued During Period Value Share Based Compensation And Related Tax Benefits Shares Delivery of Class A common stock in connection with share-based incentive compensation and related tax expense, shares Delivery of Class A common stock in connection with share-based incentive compensation and related tax benefits (in shares) Stock Issued In Exchange For Common Membership interests, Shares Stock issued in exchange for common membership interests, shares Class A common stock issued in exchange for Lazard Group common membership interests (Shares) Class A stock issued in exchange for common membership interests, shares Stock issued in exchange for common membership interests. Stock Issued In Exchange For Common Membership Interests Class A common stock issued in exchange for Lazard Group common membership interests Class A stock issued in exchange for common membership interests Repurchase of common membership interests during the period. Common Membership Interest Repurchased During Period, Value Repurchase of common membership interests from LAZ-MD Holdings Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Distributions to noncontrolling interests, net Distributions to noncontrolling interests Adjustments related to noncontrolling interests Adjustments related to noncontrolling interests Noncontrolling Interest, Period Increase (Decrease), Total Equity Component [Domain] Equity Component [Domain] Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Share-based incentive compensation and related tax benefits Employees Tax Obligations Organization And Basis Of Presentation [Abstract] Organization Consolidation And Presentation Of Financial Statements Disclosure Text Block ORGANIZATION AND BASIS OF PRESENTATION Organization And Basis Of Presentation Recent Accounting Developments [Abstract] RECENT ACCOUNTING DEVELOPMENTS Disclosure Text Block Recent Accounting Developments RECENT ACCOUNTING DEVELOPMENTS Disclosure related to receivables from fees, customer and other and related parties, net of allowance for doubtful accounts. RECEIVABLES-NET [Text Block] RECEIVABLES - NET Receivables - Net Investments [Abstract] Investment [Text Block] Investments Fair Value Measurements [Abstract] FAIR VALUE MEASUREMENTS Disclosure Text Block Fair Value Measurements Categorization of investments and certain other assets and liabilities measured at fair value on recuring basis 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 OTHER INTANGIBLE ASSETS Disclosure Text Block Goodwill And Other Intangible Assets Senior Debt [Abstract] SENIOR AND SUBORDINATED DEBT Disclosure Text Block Senior Debt Commitments And Contingencies [Abstract]