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 $29,859 and $28,777 at September 30, 2014 and December 31, 2013, respectively): Accrued Compensation And Benefits [Member] Accrued Compensation And Benefits [Member] Accrued Compensation and Benefits [Member] Accrued Fees and Other Revenue Receivable Fees 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) [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] Amortization Prepaid Compensation Asset, Amortization Amortization [Abstract] Amortization of: Adjustments Related to Tax Withholding for Share-based Compensation Tax benefit or expenses related to delivery of Class A Common Stock in connection with shared-based incentive compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition 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: Administrative And Support Services And Others [Member] Administrative And Support Services And Others [Member] Administrative and Support Services and Others Receivables [Member] Administrative Services Agreement [Member] Administrative Services Agreement [Member] Administrative Services Agreement [Member] 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 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 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 Total Assets Total Assets Assets [Abstract] ASSETS Assets, Fair Value Disclosure Total Assets Available line of credit drawn down. Available Line Of Credit Drawn Down Available line of credit drawn down Average price per share/common membership interest. Average Price Per Share Common Membership Interest Average Price Per Share/Common Membership Interest 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 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 Maximum shares issuable if performance thresholds are achieved 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 Earnout 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 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 DECREASE IN CASH AND CASH EQUIVALENTS Cash and Securities Segregated under Federal and Other Regulations Cash deposited with clearing organizations and other segregated cash Cash Distribution [Member] Lazard Ltd [Member] Certificates of Deposit, at Carrying Value Interest-bearing deposits CFLF [Member] CFLF [Member] CFLF [Member] Class of Stock [Domain] Class of Stock [Domain] COF 2. Cof Two [Member] COF2 [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 Stock, Conversion Basis Common stock conversion Common stock conversion basis 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, 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 Common Unit, Issued Membership Interests, Shares Outstanding 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 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 GROUP LLC 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): Construction in Progress [Member] Construction in Progress [Member] Conversion of Stock, Shares Converted Common stock, Class B shares conversion to Class A shares Corporate 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 Cost Savings Initiative Charges Cost Savings Initiative Charges Cost saving initiatives Cost savings initiatives CP II [Member] Cp I I [Member] CP II [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Cumulative Components [Member] Cumulative Components [Member] Cumulative [Member] Current Fiscal Year End Date Current Fiscal Year End Date 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 Disclosure [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Text Block] Senior Debt Debt Funds [Member] Debt Funds [Member] Debt Funds [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Face Amount Senior Debt, Initial Principal Amount Debt Instrument, Fair Value Disclosure Fair value of senior debt 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 Senior Debt, Maturity Date Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 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 Stock Unit [Member] Deferred Stock Unit [Member] DSUs [Member] Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] Defined Benefit Plan, Amortization of Gains (Losses) Net actuarial loss (gain) 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, 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 benefit cost (credit) Defined Benefit Plan, Net Periodic Benefit Cost [Abstract] Components of Net Benefit Cost (Credit): Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan, Service Cost Service cost Defined benefit plans expected annual employer contributions to escrow account. Defined Benefit Plans Expected Annual Employer Contributions To Escrow Account Additional contribution to escrow account Defined benefit plans expected annual employer contributions to plans. Defined Benefit Plans Expected Annual Employer Contributions To Plans Additional contribution to plan assets Delivery of common stock associated with stock awards. Delivery Of Common Stock Associated With Stock Awards Delivery of common stock associated with stock awards 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 Deposits with banks and short-term investment. Deposits with Banks and Short-Term Investment Policy [Text Block] Deposits with Banks and Short-Term Investments Deposits with Banks and Short Term Investments Deposits with Banks and Short Term Investments Deposits with banks and short-term investments Depreciation, Depletion and Amortization Depreciation and amortization of property Derivative Asset, Fair Value of Collateral Cash collateral pledged for total return swaps Derivative Asset Derivative Assets Derivatives Derivative Contract [Domain] Derivative Contract [Domain] Derivative Asset, Fair Value, Gross Asset Gross derivative assets Derivative Liability, Fair Value, Gross Liability Compensation Liability, Ending Balance Compensation Liability, Beginning Balance Gross derivative liability Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivatives Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [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 Liability Derivative Liabilities Derivatives Derivative Liability Adjustment To Forfeiture Derivative Liability Adjustment To Forfeiture Compensation Liability, Adjustment for estimated forfeitures Derivative Liability Amortizations Derivative Liability Amortizations Compensation Liability, Amortization Derivative liability, change in fair value. Derivative Liability Change In Fair Value Change in the fair value of underlying investments Compensation Liability, Increase in fair value of underlying investments 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 Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Derivatives, Policy [Policy Text Block] Derivative Instruments Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Incentive Plans Distribution Type [Axis] Distribution Type [Axis] Distribution to members and noncontrolling interests, net. Distribution To Members And Noncontrolling Interests Net Distributions to members and noncontrolling interests, net Distribution to Members One Distribution to Members One Total distributed by Lazard Group Distribution Type [Domain] Distribution Type [Domain] Dividends, Common Stock Total distributed by Lazard Group Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK) and distributions to members. Dividends Common Stock and Distributions to Members Total distributed by Lazard Group Document and Entity Information [Abstract] Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Information [Line Items] Document Information [Line Items] Document Information [Table] Document Information [Table] Document Period End Date Document Period End Date Document Type Document Type Due from Related Parties Amounts receivables from related parties Related parties Due to Related Parties Amounts payables to related parties Related party payables Due To Related Party Business Acquisitions Due To Related Party Business Acquisitions Due to related party, business acquisition Duration Of Senior Revolving Credit Facility Duration Of Senior Revolving Credit Facility Duration of senior revolving credit facility, in years Earnout Shares [Member] Earnout Shares [Member] Earnout Shares [Member] Economic interests that are owned by the management team and other investors. Economic Interests Owned By Management Team And Other Investors Economic interests that are owned by management team and other investors in the Edgewater Funds Edgewater Growth Capital Partners III, L.P. Edgewater Growth Capital Partners Three Lp [Member] EGCP III [Member] Edgewater [Member] Edgewater [Member] Edgewater [Member] Effective Income Tax Rate Reconciliation, Percent Effective income tax rates Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent U.S. federal statutory income tax rate Effect of Exchange Rate on Cash and Cash Equivalents EFFECT OF EXCHANGE RATE CHANGES ON CASH Employee Benefits and Share-based Compensation Total Employee-related Liabilities Accrued compensation and benefits Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards Settlement of vested share-based incentive compensation Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Estimated unrecognized compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Unrecognized compensation expense, years Entity Central Index Key Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity [Domain] Entity [Domain] Entity Filer Category Entity Filer Category Entity Registrant Name Entity Registrant Name Equities [Member] Equities [Member] Equities [Member]