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 By Receivable Type [Axis] Receivable Type [Axis] Accounts Payable Related Parties Current Payables to related party Accounts Receivable Net Total receivables, net 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 Accrued Compensation And Benefits [Member] Accrued Compensation And Benefits [Member] Accrued Compensation and Benefits [Member] Accrued Fees And Other Revenue Receivable Fees Accrued Liabilities Current And Noncurrent 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 [Member] Accumulated Other Comprehensive Income (Loss), Net of Tax [Member] Accumulated Translation Adjustment [Member] Currency Translation Adjustments [Member] Acquisition Related [Member] Acquisition Related [Member] Acquisition Related [Member] Additional Cash Payment Subject to Delayed Consideration Payment Additional Cash Payment Subject To Delayed Consideration Payment Additional cash payment subject to delayed payment/issuance until eighth anniversary Additional Contribution To Plan Assets Or Escrow Account Additional Contribution To Plan Assets Or Escrow Account Additional contribution to plan assets or escrow account Additional Shares Issuance Subject to Delayed Consideration Payment Additional Shares Issuance Subject To Delayed Consideration Payment Additional issuance of Class A common shares subject to delayed payment/issuance until eighth anniversary Adjustment For Amortization Prepaid Compensation Asset, Amortization Adjustment For Amortization [Abstract] Amortization of: Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value 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 operating activities: Administrative And Support Services And Others [Member] Administrative And Support Services And Others [Member] Administrative and Support Services and Others [Member] Administrative Services Agreement [Member] Administrative Services Agreement [Member] Administrative Services Agreement [Member] Administrative Services Agreement Requisite Notice Period In Days For Void Of Automatic Renewal Administrative Services Agreement Requisite Notice Period In Days For Void Of Automatic Renewal Days notice of termination 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 Aggregate Carrying Amount Noninterest Bearing Trade Receivables Aggregate Carrying Amount Noninterest Bearing Trade Receivables Aggregate carrying amount of non-interest bearing receivables Allowance For Credit Losses On Financing Receivables Table [Text Block] Schedule of Activity in Allowance for Doubtful Accounts 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] Amended Amount From Previous Escrow Arrangement Amended Amount From Previous Escrow Arrangement Amended amount from previous escrow arrangement 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 Amortization Of Interest Rate Hedge Amortization Of Interest Rate Hedge Amortization of interest rate hedge Amortization Relating To Employee Benefit Plan Amortization Relating To Employee Benefit Plan Amortization relating to employee benefit plans 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 recorded 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 Amounts recorded relating to net referral fees for underwriting, private placement, and restructuring transactions Annual Compensation Paid in Dsu Annual Compensation Paid In Dsu Annual compensation paid in DSUs Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] Asset Management Fees 1 Money management fees Asset Management Income [Member] Asset Management [Member] Asset management segment. 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] 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. 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 Benefit Obligations And Net Periodic Benefit Costs Weighted Average Assumptions And Health Care Cost Trend Rates Assumptions [Table Text Block] Benefit Obligations And Net Periodic Benefit Costs Weighted Average Assumptions And Health Care Cost Trend Rates Assumptions Table [Text Block] Schedule of Assumptions Used to Develop Actuarial Present Value of Projected Benefit Obligation and Net Periodic Pension Cost Building [Member] Buildings [Member] Business Acquisition Contingent Consideration Share Issuable Business Acquisition Contingent Consideration Share Issuable Common stock issuable on contingent basis Business Acquisition Cost Of Acquired Entity Exercised Price Business Acquisition Cost Of Acquired Entity Exercised Price Business acquisition, cost of acquired entity, exercised price Business Acquisition Earnout Share Unrestricted or Delivered Business Acquisition Earnout Share Unrestricted Or Delivered Earnout shares earned Business Acquisition Effective Date Of Acquisition 1 Date the remaining option to purchase North American fund management is exercisable Business Acquisition Equity Interests Issued Or Issuable Number Of Shares Issued Additional shares issued and subject to earnout criteria and payable over time Business Acquisition Non Contingent Consideration Number Of Shares Delivered Business Acquisition Non Contingent Consideration Number Of Shares Delivered Common stock delivered on non-contingent basis Business Acquisition, Non Contingent Consideration, Shares Issuable Business Acquisition Non Contingent Consideration Shares Issuable Common stock issuable on non-contingent basis Business acquisition number of common stock issued Business Acquisition Number Of Common Stock Issued Business acquisition number of common stock issued Business Acquisition Option Cost To Acquire Entity Purchase Price Business Acquisition Option Cost To Acquire Entity Purchase Price Business Acquisition - option cost to acquire entity, purchase price Business Acquisitions And Related Equity Transactions [Abstract] Business Acquisitions And Related Equity Transactions [Abstract] Business acquisitions and related equity transactions: Business Acquisition Share Issued For Earn Out Shares Settled Business Acquisition Share Issued For Earn Out Shares Settled Earnout shares became settled Business Alliance Agreement [Member] Business Alliance Agreement [Member] Business Alliance Agreement [Member] Business Development Marketing and business development Capital Contributions To Subsidiaries Capital Contributions To Subsidiaries Capital contribution to subsidiaries 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 Current Minimum Rental Commitments Capital - 2014 Capital Leases Future Minimum Payments Due In Five Years Minimum Rental Commitments Capital - 2018 Capital Leases Future Minimum Payments Due In Four Years Minimum Rental Commitments Capital - 2017 Capital Leases Future Minimum Payments Due In Three Years Minimum Rental Commitments Capital - 2016 Capital Leases Future Minimum Payments Due In Two Years Minimum Rental Commitments Capital - 2015 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 Carrying Reported Amount Fair Value Disclosure [Member] Carrying Value [Member] Cash And Alternative Investment [Member] Cash And Alternative Investment [Member] Cash and Alternative Investment [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 Maturity Description Cash And Cash Equivalents Maturity Description Cash and cash equivalents maturity period Cash And Cash Equivalents Period Increase Decrease NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS Cash And Cash Equivalents Policy [Text Block] Cash and Cash Equivalents Cash And Cash Equivalents Restricted Cash And Cash Equivalents Policy 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 Year [Abstract] Cash Paid During Year [Abstract] Cash paid during the year for: Certificates Of Deposit At Carrying Value Interest-bearing deposits Interest-bearing deposits (included within investments) CFLF. Cflf [Member] CFLF [Member] Change In Benefit Obligation [Member] Change In Benefit Obligation [Member] Change in Benefit Obligation [Member] Change in fair value of compensation liability. Change In Fair Value Of Compensation Liability Change in the fair value of underlying investments Change In Plan Assets Due To Purchases Change In Plan Assets Due To Purchases Change in plan assets due to purchases Change In Plan Assets [Member] Change In Plan Assets [Member] Change in Plan Assets [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 Or Realized Gains Or 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 and losses Class Of Stock [Domain] Class of Stock [Domain] COF 2. Cof Two [Member] COF2 [Member] Collateralized Financings Collateralized borrowing activities 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 Common membership 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 during the period. Common Membership Interest Repurchased During Period Value Repurchase of common membership interests from LAZ-MD Holdings Common membership interests issued in connection with business acquisitions. Common Membership Interests Issued In Connection With Business Acquisitions Common membership interests issued Number of shares outstanding in common membership interests. Common Membership Interests Shares Outstanding Common Membership Interests, Shares Outstanding 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 Issued For Merger Common Stock Issued For Merger Issue of Class A common stock Common Stock Of Parent Held By Subsidiary Common Stock Of Parent Held By Subsidiary Common stock of parent held by Lazard Group 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 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 Asset Management Funds Fair Value Of Investments Funds Company Fund Interests In Alternative Asset Management Funds Fair Value Of Investments Funds Lazard fund interests in alternative investments funds Company Other Distributions Company Other Distributions Company other distributions Company Share Other Comprehensive Income Loss Net Of Tax Company Share Other Comprehensive Income Loss Net Of Tax Net other comprehensive income (loss) 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 Net Of Tax COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD GROUP LLC Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest COMPREHENSIVE INCOME Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract] Comprehensive income (loss): Comprehensive Income Policy Policy [Text Block] Reclassifications out of Accumulated Other Comprehensive Income Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk By Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Percentage 1 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] Construction In Progress [Member] Construction in Progress [Member] Contingencies And Commitments [Line Items] Contingencies And Commitments [Line Items] Contingencies And Commitments [Line Items] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contractual Payment Term Description Contractual Payment Term Description Contractual payment term description relating to our interest-bearing financing receivables Corporate [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 [Text Block] Cost-Saving Initiatives and Staff Reductions Cost Savings Initiative Charges Cost Savings Initiative Charges 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 Tax Receivables And Deferred Tax Assets And Other Taxes Current Tax Receivables And Deferred Tax Assets And Other Taxes Current tax receivables and deferred tax assets (net of valuation allowance) and other taxes Daily [Member] Daily [Member] Daily [Member] Days fee receivables are considered past due in excess. Days Fee Receivables Considered Past Due In Excess Days fee receivables are considered past due in excess Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Text Block] Senior and Subordinated Debt Debt Funds [Member] Debt Funds [Member] Debt Funds [Member] Debt Instrument Face 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 Senior Debt, Maturity Date Debt Instrument Redemption [Line Items] Debt Instrument, Redemption [Line Items] Debt Instrument Redemption [Table] Debt Instrument Redemption [Table] Debt Instrument Repurchased Face Amount Promissory note representing subordinated debt, repurchased Debt Instrument [Table] Schedule of Long-term Debt Instruments [Table] Debt Securities [Member] Debt [Member] December Two Thousand Fifteen [Member] December Two Thousand Fifteen [Member] December 2015 [Member] December Two Thousand Fourteen [Member] December Two Thousand Fourteen [Member] December 2014 [Member] Deferred Compensation Arrangements [Abstract] Deferred Compensation Arrangements [Abstract] Deferred Compensation Arrangement With Individual Postretirement Benefits By Type Of Deferred Compensation [Axis] Postretirement Benefits, 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 Current And Noncurrent 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 awards A deferred tax asset is recognized if it is more likely than not (defined as a likelihood of greater than 50%) that a tax benefit will be accepted by a taxing authority. Deferred Income Tax Assets Benefits Percentage A deferred tax asset is recognized if it is more likely than not (defined as a likelihood of greater than 50%) that a tax benefit will be accepted by a taxing authority. Deferred Income Taxes And Other Tax Liabilities Deferred Income Taxes And Other Tax Liabilities Current and deferred income taxes and other taxes Deferred Income Tax Expense Benefit Deferred tax benefit Total deferred Deferred Revenue Leases Current Deferred lease incentives Deferred State And Local Income Tax Expense Benefit State and local (primarily UBT), deferred