Abandoned Leased Space Abandoned Leased Space Abandoned leased space (principally in the U.K.) Accounting Changes and Error Corrections [Abstract] Accounting Changes and Error Corrections [Abstract] Accounting Policies [Abstract] Accounting Policies [Abstract] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Receivable Type [Axis] Receivable Type [Axis] Accounts Payable, Related Parties, Current Payables to related party Accounts Receivable, Net Total receivables, net Accounts Receivable, Net [Abstract] Receivables (net of allowance for doubtful accounts of $23,540 and $28,777 at December 31, 2014 and 2013, respectively): Accrued Compensation And Benefits [Member] Accrued Compensation And Benefits [Member] Accrued Compensation and Benefits [Member] Accrued Fees and Other Revenue Receivable Fees Accrued Liabilities Accrued expenses Accumulated Defined Benefit Plans Adjustment [Member] Employee Benefit Plans [Member] Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less - Accumulated depreciation and amortization Property, accumulated amortization and depreciation Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss), Net of Tax Ending balance Beginning balance Accumulated other comprehensive loss, net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Other Comprehensive Income (Loss), Net of Tax [Member] Accumulated Translation Adjustment [Member] Currency Translation Adjustments [Member] Additional Cash and Cash Equivalent Related Text Cash and cash equivalents maturity period Additional Paid in Capital Additional paid-in-capital Additional Paid-in Capital [Member] Additional Paid-In-Capital [Member] Adjustment associated with Class A common stock issuable on a non-contingent basis Adjustment Associated With Class Common Stock Issuable On Non Contingent Basis Add (deduct) - adjustment associated with Class A common stock issuable on a non-contingent basis Amortization Prepaid Compensation Asset, Amortization Amortization [Abstract] Amortization of: Adjustments Related to Tax Withholding for Share-based Compensation Tax benefit related to delivery of Class A Common Stock in connection with share-based incentive compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Amortization of share-based incentive compensation Share-based incentive awards Adjustments to income relating to interest expense and changes in net income attributable to noncontrolling interests from issuance of stock, net of tax Adjustments To Income Relating To Interest Expense And Changes In Net Income Attributable To Noncontrolling Interests From Issuance Of Stock Net Of Tax Adjustments to income relating to interest expense and changes in net income attributable to noncontrolling interests resulting from assumed Class A common stock issuances in connection with share-based incentive compensation, and exchangeable interests, net of tax 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: Adjustments to reconcile net income to net cash provided by operating activities: Administrative And Support Services And Others [Member] Administrative And Support Services And Others [Member] Administrative and Support Services and Other Receivables [Member] Administrative Services Agreement [Member] Administrative Services Agreement [Member] Administrative Services Agreement [Member] Advances and prepayments Advances And Prepayments Other advances and prepayments Aggregate amount in account security arrangement. Aggregate Amount In Account Security Arrangement Aggregate amount in account security arrangement The aggregate carrying amount of non-interest bearing trade receivables. Aggregate Carrying Amount Noninterest Bearing Trade Receivables Aggregate carrying amount of non-interest bearing receivables Allowance for Doubtful Accounts Receivable Allowance for doubtful accounts receivables, Ending balance Allowance for doubtful accounts receivables, Beginning balance Allowance for doubtful accounts receivables Allowance for doubtful accounts receivable charge offs, foreign currency translation and other adjustments. Allowance For Doubtful Accounts Receivable Charge Offs Foreign Currency Translation And Other Adjustments Charge-offs, foreign currency translation and other adjustments Alternative Investments, Fair Value Disclosure Fair Value Alternative Investments [Member] Alternative Investments [Member] Alternative Investment Funds [Member] Amendment Flag Amendment Flag Amortization, grants of awards for current employees. Amortization Grants Of Awards Amortization, net 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 expense of intangible assets Amortization of intangible assets related to acquisitions Amount of Deferred Tax Assets for Unrecognized Tax Benefits Recorded. Amount Of Deferred Tax Assets For Unrecognized Tax Benefits Recorded Amount of deferred tax assets for unrecognized tax benefits, including interest and penalties recorded that may be recognized within 12 months Amount Recorded in Accrued Compensation Expense Related to Liability Award After Amortization Amount Recorded in Accrued Compensation Expense Related to Liability Award After Amortization Amount recorded in accrued compensation expense related to liability award after amortization 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 Net referral fees for underwriting, private placement, M&A and restructuring transactions Annual compensation paid in DSUs. Annual Compensation Paid in Dsu Annual compensation paid in DSUs Annual Date Of Goodwill Impairment Annual Date Of Goodwill Impairment Annual date of goodwill impairment Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Asset Management Fees Asset management fees Asset Management Income [Member] Asset Management [Member] Asset Management segment [Member] Asset Management Segment [Member] Asset Management Segment [Member] Assets Identifiable Assets Total Assets Total Assets Assets [Abstract] ASSETS Assets, Fair Value Disclosure Total Assets Assets Management [Member] Assets Management [Member] Asset Management [Member] Available line of credit drawn down. Available Line Of Credit Drawn Down Available line of credit drawn down Available Line Of Credit Payback Available Line Of Credit Payback Available line of credit payback Average price per share/common membership interest. Average Price Per Share Common Membership Interest Average Price Per Share Awarded Under Two Thousand Eight Plan [Member] Awarded Under Two Thousand Eight Plan [Member] Awarded Under 2008 Plan [Member] Award Type [Axis] Award Type [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Banking and Thrift [Abstract] Banking and Thrift [Abstract] Basis of Presentation and Significant Accounting Policies [Text Block] Basis of Presentation Basis Step Up Assets Related To Tax Receivable Agreement. Basis Step Up Assets Related To Tax Receivable Agreement Basis step-up assets Building [Member] Buildings [Member] Business Acquisition Contingent Consideration Initial and Earnout Shares Issuable Business Acquisition Contingent Consideration Initial And Earnout Shares Issuable Initial and Earnout shares issuable on contingent basis Business Acquisition Contingent Consideration Share Issuable. Business Acquisition Contingent Consideration Share Issuable Common stock issuable on contingent basis Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Additional shares issued and subject to earnout criteria and payable over time Business acquisition initial and earn-out shares unrestricted or delivered. Business Acquisition Initial and Earnout Shares Unrestricted or Delivered Initial and Earnout shares earned Business Acquisition, Non Contingent Consideration, Shares Issuable Business Acquisition, Non Contingent Consideration, Shares Issuable Common stock issuable on non-contingent basis Business Acquisition Non Contingent Consideration Shares Issued Business Acquisition Non Contingent Consideration Shares Issued Common stock issued on non-contingent basis Business acquisitions and related equity transactions. Business Acquisitions And Related Equity Transactions [Abstract] Business acquisitions and related equity transactions: Business Acquisition Share Issued For Initial and Earn Out Shares Settled Business Acquisition Share Issued For Initial And Earn Out Shares Settled Initial and Earnout shares became settled Business Combination, Consideration Transferred Aggregate fair value of consideration recognized by the company at acquisition date Business Development Marketing and business development Capital Regulatory capital Capital Lease Obligation Collateralized Capital Lease Obligation Collateralized Obligations collateralized by certain assets with a net book value Capital Lease Obligations Capital lease obligations Capital Lease Obligations Recorded Under Sale Leaseback Transactions Payable Capital Lease Obligations Recorded Under Sale Leaseback Transactions Payable Capital lease obligation payable through Capital Leases, Balance Sheet, Assets by Major Class, Net Book value of assets under capital lease Capital Leases, Future Minimum Payments Due Total minimum lease payments - Capital Capital Leases, Future Minimum Payments Due, Next Twelve Months Minimum Rental Commitments Capital - 2015 Capital Leases, Future Minimum Payments Due in Five Years Minimum Rental Commitments Capital - 2019 Capital Leases, Future Minimum Payments Due in Four Years Minimum Rental Commitments Capital - 2018 Capital Leases, Future Minimum Payments Due in Three Years Minimum Rental Commitments Capital - 2017 Capital Leases, Future Minimum Payments Due in Two Years Minimum Rental Commitments Capital - 2016 Capital Leases, Future Minimum Payments Due Thereafter Minimum Rental Commitments Capital - Thereafter Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments Present value of capital lease commitments Capital Leases, Income Statement, Interest Expense Less amount representing interest Reported Value Measurement [Member] Carrying Value [Member] Cash and alternative investment funds. Cash And Alternative Investment Funds [Member] Cash And Alternative Investment Funds [Member] Cash and Cash Equivalents, at Carrying Value CASH AND CASH EQUIVALENTS-December 31 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 Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Cash Deposited with Clearing Organizations and Other Segregated Cash Cash and Securities Segregated under Federal and Other Regulations Cash deposited with clearing organizations and other segregated cash Cash [Member] Cash [Member] Cash paid during the year [Abstract] Cash Paid During Year [Abstract] Cash paid during the year for: Certain Net Operating Loss And Tax Credit Carryforwards Certain Net Operating Loss And Tax Credit Carryforwards Net operating loss and tax credit carryforwards Certificates of Deposit, at Carrying Value Interest-bearing deposits Interest-bearing deposits (included within investments) CFLF [Member] CFLF [Member] CFLF [Member] Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block] Summary of Changes in Benefit Obligations, Fair Value of Assets, Funded Status and Amounts Recognized in Consolidated Statements of Financial Condition Changes to Fair value of plans assets due to net unrealized/realized gains/losses. Changes To Fair Value Of Plans Assets Due To Net Unrealized Or Realized Gains Or Losses Change in fair value of plan assets due to net unrealized/realized gains (losses) Charge To Retained Earnings Pertaining To Issuance Of Restricted Stock Units In Connection With Participation Rights Charge To Retained Earnings Pertaining To Issuance Of Restricted Stock Units In Connection With Participation Rights Charges to retained earnings, net of estimated forfeitures Class A common stock issued in exchange for subsidiary common membership interests, shares Class Common Stock Issued In Exchange For Subsidiary Common Membership Interests Shares Class A common stock issued in exchange for Lazard Group common membership interests (in shares) Shares in exchanges of a like number of common membership interests Class A common stock issued in exchange for subsidiary common membership interests, value. Class Common Stock Issued In Exchange For Subsidiary Common Membership Interests Value Class A common stock issued in exchange for Lazard Group common membership interests Class of Stock [Domain] Class of Stock [Domain] COF 2. Cof Two [Member] COF2 [Member] Combined European Regulated Group [Member] Combined European Regulated Group [Member] Combined European Regulated Group [Member] Commitments and Contingencies Commitments and contingencies Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] 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 Issued Common Membership Interest Issued Ending balance (in shares) Common Membership Interest Ownership Percentage Common Membership Interest Ownership Percentage Percentage of Ownership, Ending Balance Percentage of common membership interests held Common Stock, Conversion Basis Common stock conversion Common stock conversion basis Common Stock, Dividends, Per Share, Declared Dividend declared per share of common stock DIVIDENDS DECLARED PER SHARE OF COMMON STOCK Common Stock Held by Subsidiary Class A common stock held by subsidiaries, at cost Class A common stock held by subsidiaries, at cost (7,450,745 and 8,317,065 shares at December 31, 2014 and 2013, respectively) Common Stock Held by Subsidiary Common Stock Held By Subsidiary [Member] Class A Common Stock Held By Subsidiaries [Member] 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 Common stock held by subsidiaries, shares Common Stock [Member] Common Stock [Member] Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] Common stock: Common Stock, Par or Stated Value Per Share Common stock, par value Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, issued Common stock, shares issued Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock Special Dividends Per Share Declared Common Stock Special Dividends Per Share Declared Special dividend declared per share of common stock Common Stock, Value, Issued Common stock Company Fund Interest Debt Funds Company Fund Interest Debt Funds Lazard fund interests in debt funds Company Fund Interests Equities Funds Company Fund Interests Equities Funds Lazard fund interests in equities funds Company fund interests in alternative investment funds. Company Fund Interests In Alternative Investment Funds Lazard fund interests in alternative investments funds Company other distributions Company Other Distributions Company other distributions Company tax distributions Company Tax Distributions Company tax distributions Compensation And Benefits [Member] Compensation And Benefits [Member] Compensation and Benefits [Member] Compensation and Retirement Disclosure [Abstract] Compensation and Retirement Disclosure [Abstract] Comprehensive Income (Loss), Net of Tax, Attributable to Parent COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD LTD Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Comprehensive income (loss): Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk, Percentage Individual clients did not constitute more than a specific percentage of net revenue Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Financial Information of Parent Company Only Disclosure [Text Block] Schedule I - Condensed Financial Information of Registrant (Parent Company Only) Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Construction in Progress [Member] Construction in Progress [Member] Contractual Payment Term Description Contractual Payment Term Description Contractual payment term description relating to our interest-bearing financing receivables Conversion of Stock, Shares Converted Common stock, Class B shares conversion to Class A shares Corporate, Non-Segment [Member] Corporate [Member] Cost of Reimbursable Expense Amounts recorded relating to the administrative services agreement Costs and Expenses Operating expenses Total operating expenses Costs and Expenses [Abstract] OPERATING EXPENSES Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block] Cost Saving Initiatives and Staff Reductions CP II [Member] Cp I I [Member] CP II [Member] Cumulative Components [Member] Cumulative Components [Member] Cumulative [Member] Current Federal Tax Expense (Benefit) Federal, current Current Fiscal Year End Date Current Fiscal Year End Date Current Foreign Tax Expense (Benefit) Foreign, current Current Income Tax Expense (Benefit) Total current Current State and Local Tax Expense (Benefit) State and local (primarily UBT), current Current year reclassifications, (including noncontrolling interests) from accumulated other comprehensive income current period net of tax. Current Year Reclassifications, (Including Noncontrolling Interests) From Accumulated Other Comprehensive Income Current Period Net Of Tax Total reclassifications, net of tax Daily [Member] Daily [Member] Daily [Member] Debt and debt funds. Debt And Debt Funds [Member] Debt And Debt Funds [Member] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Text Block] Senior Debt Debt Funds [Member] Debt Funds [Member] Debt Funds [Member] Debt Instrument, Face Amount Senior debt aggregate principal amount Senior Debt, Initial Principal Amount Debt Instrument Interest Rate Payment Date Debt Instrument Interest Rate Payment Date Interest rate, payment terms Debt Instrument, Interest Rate, Stated Percentage Senior Debt, Annual Interest Rate Senior notes interest rate Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument, Maturity Date Original Maturity Date Senior Debt, Maturity Date Debt Instrument Maturity Year Debt Instrument Maturity Year Senior notes due Debt Instrument, Redemption [Line Items] Debt Instrument, Redemption [Line Items] Debt Instrument Redemption [Table] Debt Instrument Redemption [Table] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Securities [Member] Debt [Member] Decrease In Sublease Income Decrease In Sublease Income Decreased sublease income Deferred Compensation Arrangements [Abstract] Deferred Compensation Arrangements [Abstract] Deferred Compensation Arrangement with Individual, Allocated Share-based Compensation Expense Total Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Deferred Costs Deferred debt issuance costs Deferred Federal Income Tax Expense (Benefit) Federal, deferred Deferred Foreign Income Tax Expense (Benefit) Foreign, deferred Deferred Incentive Awards. Deferred Incentive Awards Deferred incentive compensation awards excluding PRSUs Deferred Income Taxes And Other Tax Liabilities Deferred Income Taxes And Other Tax Liabilities Current and deferred income taxes and other taxes Deferred Income Taxes and Other Tax Receivable, Current Current tax receivables and deferred tax assets (net of valuation allowance) and other taxes Deferred Income Tax Expense (Benefit) Deferred tax provision (benefit) Total deferred Deferred Revenue Deferred revenue Deferred Revenue, Leases, Current Deferred lease incentives Deferred State and Local Income Tax Expense (Benefit) State and local (primarily UBT), deferred