Derivative Instruments and Hedging Activities Disclosure [Abstract] A- or higher Fair Value Of Over Counter Derivatives Assets Counterparty Credit QualityA Or Higher Fair Value Of Over Counter Derivatives Assets Counterparty Credit QualityA Or Higher BBB- to BBB Fair Value Of Over Counter Derivatives Assets Counterparty Credit Quality Bbb To Bbb Fair value of OTC derivatives assets, counterparty credit quality BBB- to BBB. BB or lower Fair Value Of Over Counter Derivatives Assets Counterparty Credit Quality Bb or Lower Fair value of OTC derivatives assets, counterparty credit quality BB or lower. Unrated Fair Value Of Over Counter Derivatives Assets Counterparty Credit Quality Unrated Fair value of OTC derivatives assets, counterparty credit quality unrated. Total OTC derivative assets included in Financial instruments owned Otc Derivative Assets Included In Financial Instruments Owned OTC Derivative Assets Included In Financial Instruments Owned. Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Epic Gas Epic Gas [Member] Epic Gas [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Ownership percentage Equity Method Investment, Ownership Percentage Proceeds from sale of Epic Gas Proceeds from Sale of Equity Method Investments Gain on sale of Epic Gas Equity Method Investment, Realized Gain (Loss) on Disposal Our investment in Epic Gas Equity Method Investments Net earnings (losses) Equity Method Investment, Summarized Financial Information, Net Income (Loss) Segment Reporting [Abstract] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Americas Americas [Member] Europe Europe [Member] Asia Asia [Member] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Revenues: Revenues [Abstract] Net revenues Revenues, Net of Interest Expense Debt Disclosure [Abstract] Long-Term Debt Long-term Debt [Text Block] Compensation Related Costs [Abstract] Compensation Plans Compensation Related Costs, General [Text Block] Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Promissory Note Promissory Note [Member] Promissory Note [Member] Jefferies Finance, LLC Jefferies Finance Llc [Member] Jefferies Finance LLC. Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Assets Other Assets [Member] Accrued expense and other liabilities Accrued Expense And Other Liabilities [Member] Accrued Expense And Other Liabilities [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Corporate debt securities Corporate Debt Securities [Member] Guarantee Obligations [Line Items] Guarantor Obligations [Line Items] Equity commitment Equity Commitment, Amount Equity Commitment, Amount Total committed equity capitalization of JFIN Commitments Under Equity Capitalization Of Joint Venture Entity Commitments under equity capitalization of joint venture entity. Funded portion of equity commitment to subsidiary Equity Commitment To Joint Venture Funded Portion Equity commitment to joint venture funded portion. Unfunded portion of equity commitment to subsidiary Equity Commitment To Joint Venture Unfunded Portion Equity commitment to joint venture unfunded portion. Extension period Line Of Credit Extension Period Line of credit extension period. Termination notice period Line Of Credit Termination Notice Period Line of credit termination notice period. Committed line of credit facility amount Line Of Credit Facility Commitment Under Joint Venture Line of credit facility commitment under joint venture. Funded portion of loan commitment Loan Commitment To Joint Venture Funded Portion Loan Commitment To Joint Venture Funded Portion Loan commitment Aggregate Loan Commitment Aggregate loan commitment to joint venture. Receivables under service agreement Due from Related Parties Payables under service agreement Due to Related Parties Financial instruments owned, at fair value Financial Instruments, Owned, at Fair Value Payables—brokers, dealers and clearing organizations Payables to Broker-Dealers and Clearing Organizations Financial instruments sold, not yet purchased, at fair value Financial Instruments Sold, Not yet Purchased, at Fair Value Debt principal amount Debt Instrument, Face Amount Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Member's paid-in capital Additional Paid-in Capital [Member] Accumulated other comprehensive income (loss) AOCI Attributable to Parent [Member] Total Jefferies Group LLC member’s equity Parent [Member] Noncontrolling interests Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, beginning of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Cumulative effect of the adoption of the new revenue standard, net of tax Cumulative Effect of New Accounting Principle in Period of Adoption Net earnings (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Distribution to Jefferies Financial Group Inc. Distributed Earnings Tax Cuts and Jobs Act adjustment Tax Cuts And Jobs Act of 2017, Reclassification from Aoci to Additional Paid-in Capital Tax Effect Tax Cuts And Jobs Act of 2017, Reclassification from Aoci to Additional Paid-in Capital Tax Effect Currency adjustments and other Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Changes in instrument specific credit risk Other Comprehensive Income Loss Changes in Instrument Specific Credit Risk, Net of Tax Other Comprehensive Income (Loss) Changes in Instrument Specific Credit Risk, Net of Tax Cash flow hedges Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Unrealized gain on available-for-sale securities Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Contributions Noncontrolling Interest, Increase from Subsidiary Equity Issuance Distributions Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Balance, end of period Revenue from Contract with Customer [Abstract] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Equities Equities [Member] Equities [Member] Fixed Income Fixed Income Services [Member] Fixed Income Services [Member] Investment banking - Capital markets Investment Banking, Capital Markets [Member] Investment Banking, Capital Markets [Member] Investment banking - Advisory Investment Banking, Advisory [Member] Investment Banking, Advisory [Member] Asset management Asset Management Services [Member] Asset Management Services [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Capital Markets Capital Markets [Member] Capital markets. Asset Management Asset Management Segment [Member] Asset Management Segment [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenues from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Non-interest expenses Noninterest Expense Earnings before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Segment assets Assets Fair Value Disclosures [Abstract] Financial instruments owned: Financial Instruments, Owned, at Fair Value [Abstract] Loans and other receivables Fair Value, Option, Aggregate Differences, Loans and Long-term Receivables Loans and other receivables on nonaccrual status and/or 90 days or greater past due Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status, Aggregated Difference Long-term debt Fair Value, Option, Aggregate Differences, Long-term And Short-Term Debt Instruments Fair Value, Option, Aggregate Differences, Long-term And Short-Term Debt Instruments Loans and other receivables 90 days or greater past due Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due, Aggregate Difference Commitments and Contingencies Disclosure [Abstract] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Derivative contracts—non-credit related Derivative Contracts Non Credit Related [Member] Derivative contracts - non credit related. Written derivative contracts—credit related Derivative Contracts Credit Related [Member] Derivative contracts - credit related. Total derivative contracts Derivative [Member] 2019 Guarantees Expected To Be Due Current Guarantees with a remaining term that matures during the fiscal year. These may include derivative guarantees, etc. 2020 Guarantees Expected To Be Due In Two Years Guarantees expected to be due within 2 fiscal years. These may include, derivative guarantees, etc. 2021 and 2022 Guarantees Expected To Be Due In Three And Four Years Guarantees expected to be due within 3 to 4 fiscal years. These may include, derivative guarantees, etc. 2023 and 2024 Guarantees Expected To Be Due In Five And Six Years Guarantees expected to be due within 5 to 6 fiscal years. These may include, derivative guarantees, etc. 2025 and Later Guarantees Expected To Be Due Thereafter Guarantees expected to be due within 7 fiscal years and thereafter. These may include, derivative guarantees, etc Notional/ Maximum Payout Guarantor Obligations, Maximum Exposure, Undiscounted Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Investment Redemption Prior Written Notice Period [Axis] Investment Redemption Prior Written Notice Period [Axis] Investment Redemption Prior Written Notice Period [Axis] Investment Redemption Prior Written Notice Period [Domain] Investment Redemption Prior Written Notice Period [Domain] [Domain] for Investment Redemption Prior Written Notice Period [Axis] 45 - 90 days prior written notice 45 To 90 Days Prior Written Notice [Member] 45 To 90 Days Prior Written Notice [Member] 60 days prior written notice 60 Days Prior Written Notice [Member] 60 Days Prior Written Notice [Member] Equity Long/Short Hedge Funds Hedge Funds, Equity Long (Short) [Member] Equity Funds Private Equity Funds [Member] Commodity Funds Commodity Funds [Member] Commodity Funds [Member] Multi-asset Funds Multi-asset Funds [Member] Multi-asset Funds [Member] Other Funds Other Funds [Member] Other Funds [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] Fair Value Alternative Investment Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Percentage of investment at fair value, redemption restriction Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction, Percentage Investments redemption restriction period Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction, Period in Effect Investments redemption restriction period remaining Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction Period Percentage of redeemable investments Redeemable Investments Investments redeemable within 60-90 days Notice period redemption of investment prior written notice period Notice Period Redemption Of Investments Prior Written Notice Period Investments at fair value that cannot be redeemed at reporting date and are subject to a prior written redemption request. Expected period for the liquidation of the underlying assets, minimum Expected Period For Liquidation Of Underlying Assets Minimum Expected Period For Liquidation Of Underlying Assets Minimum Expected period for the liquidation of the underlying assets, maximum Expected Period For Liquidation Of Underlying Assets Maximum Expected Period For Liquidation Of Underlying Assets Maximum Segment Reporting Segment Reporting Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Number of operating segments Number of Operating Segments Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Statement of Comprehensive Income [Abstract] Currency translation and other adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Changes in instrument specific credit risk Accumulated Changes In Instrument Specific Credit Risk Attributable To Parent [Member] Accumulated Changes In Instrument Specific Credit Risk Attributable To Parent [Member] Cash flow hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Domain] Retirement Plan Sponsor Location [Domain] German Plan Foreign Plan [Member] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Plan Pension Plan [Member] Impact of certain discrete items related to non-U.S. subsidiaries planning for the Tax Act Tax Cuts And Jobs Act Of 2017 Incomplete Accounting Provisional Income Tax Expense (Benefit) Amount of reasonable estimate for income tax expense (benefit) from effect of Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete. Currency translation and other adjustments Reclassification amount related to the Tax Cuts and Jobs Act Tax Cuts And Jobs Act Of 2017 Reclassification From Aoci To Retained Earnings Tax Effect Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017. Changes in instrument specific credit risk, tax expense Other Comprehensive Income (Loss), Changes in Instrument Specific Credit Risk, Tax Other Comprehensive Income (Loss), Changes in Instrument Specific Credit Risk, Tax Changes in instrument specific credit risk reclassified to earnings Other Comprehensive Income (Loss) Changes In Instrument Specific Credit Risk Reclassified To Earnings, Net of Tax Other Comprehensive Income (Loss) Changes In Instrument Specific Credit Risk Reclassified To Earnings, Net of Tax Changes in instrument specific credit risk reclassified to earnings, tax Other Comprehensive Income (Loss) Changes In Instrument Specific Credit Risk Reclassified To Earnings, Tax Other Comprehensive Income (Loss) Changes In Instrument Specific Credit Risk Reclassified To Earnings, Tax Cash flow hedges, tax expense (benefit) Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Unrealized gain on available-for-sale securities, tax expense Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Schedule of Gain (Loss) on Securities [Table] Schedule of Gain (Loss) on Securities [Table] Securities or Other Assets Sold under Agreements to Repurchase [Axis] Securities or Other Assets Sold under Agreements to Repurchase [Axis] Assets Sold under Agreements to Repurchase, Type [Domain] Assets Sold under Agreements to Repurchase, Type [Domain] Loans Loans [Member] Loan commitments Loan Commitments [Member] Loan commitments. Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Long-term debt Long-term Debt [Member] Gain (Loss) on Securities [Line Items] Gain (Loss) on Securities [Line Items] Loans and other receivables Fair Value, Option, Credit Risk, Gains (Losses) on Assets Financial instruments sold, not yet purchased and Long-term debt Financial Instruments Sold, Not yet Purchased, at Fair Value [Abstract] Changes in instrument specific credit risk Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Reclassification Adjustment from AOCI for Derecognition, after Tax Other changes in fair value Fair Value, Option, Changes in Fair Value, Gain (Loss) JCP Fund V JCP Funds [Member] JCP Funds [Member] Total committed equity capitalization Percent of financial information presented Equity Method Investment, Percent of Financial Information Presented Equity Method Investment, Percent of Financial Information Presented Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Nonconsolidated VIEs Variable Interest Entity, Not Primary Beneficiary [Member] CLOs Collateralized Loan Obligations [Member] Consumer loan and other asset-backed vehicles Consumer Loan And Other Asset-Backed Vehicles [Member] Consumer Loan And Other Asset-Backed Vehicles [Member] Related party private equity vehicles Private Equity Vehicles [Member] Private equity vehicles. Other investment vehicles Other Investment Vehicles [Member] Other Investment Vehicles [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Carrying Amount, Assets Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets Carrying Amount, Liabilities Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities Maximum Exposure to Loss Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount VIE Assets Variable Interest Entity Carrying Amount Of Assets Non Consolidated Vie Variable Interest Entity Carrying Amount Of Assets Non Consolidated Vie Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Berkadia Commercial Mortgage, LLC Berkadia Commercial Mortgage, LLC [Member] Berkadia Commercial Mortgage, LLC [Member] Our total equity balance Net earnings (loss) Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Investments Measured at Fair Value Based on Net Asset Value Per Share Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block] Summary of Changes in Fair Value of Financial Assets and Liabilities Classified as Level 3 Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Table [Table Text Block] Reconciliation of beginning Level 3 assets and liabilities to ending Level 3 assets and liabilities (specifically disaggregating purchases, sales, settlements, issuances, transfers to Level 3 and transfers out of Level 3). Quantitative Information about Significant Unobservable Inputs Used in Level 3 Fair Value Measurements Fair Value Inputs Assets And Liabilities Quantitative Information Table [Table Text Block] Tabular disclosure of quantitative information about significant unobservable inputs used in the fair value measurement of Level 3 financial assets and liabilities, including valuation technique and range of inputs Summary of Gains (Losses) Due to Changes in Instrument Specific Credit Risk and Summary of Contractual Principal Exceeds Fair Value for Loans and Other Receivables Fair Value Option, Disclosures [Table Text Block] Commissions and other fees Commissions And Other Fees [Member] Commissions And Other Fees [Member] Investment banking Investment Banking [Member] Investment Banking [Member] Asset management fees Asset Management Fees [Member] Asset Management Fees [Member] Other Revenue From Contract With Customers, Other [Member] Revenue From Contract With Customers, Other [Member] Principal transactions Principal Transactions Revenue [Member] Principal Transactions Revenue [Member] Interest Interest Revenue [Member] Interest Revenue [Member] Other Other Sources Of Revenue, Miscellaneous [Member] Other Sources Of Revenue, Miscellaneous [Member] Revenues Revenues Banking and Thrift [Abstract] Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Table] Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Table] Corporate equity securities Equity Securities [Member] Mortgage- and asset-backed securities Mortgage and Asset-Backed Securities [Member] Mortgage and Asset-Backed Securities [Member] U.S. government and federal agency securities US Government Corporations and Agencies Securities [Member] Municipal securities Municipal Bonds [Member] Sovereign obligations Sovereign Debt [Member] Loans and other receivables Loans and Finance Receivables [Member] Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items] Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] Securities Lending Arrangements Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred Repurchase Agreements Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement Total Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement Accounting Policies [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Jefferies Bache Limited Jefferies Bache Limited [Member] Jefferies Bache Limited [Member] GERMANY GERMANY Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Affiliated Entity Affiliated Entity [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Jefferies Jefferies Financial Group Inc. [Member] Jefferies Financial Group Inc. [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Defined benefit pension obligations and insurance contracts transfer amount Defined Benefit Plan, Business Combinations And Acquisition, Pension Obligations And Insurance Contracts Transfer Amount Defined Benefit Plan, Business Combinations And Acquisition, Pension Obligations And Insurance Contracts Transfer Amount Consideration for release of indemnity relating to pension obligations Consideration For Release of Indemnity Relating To Pension Obligations Consideration For Release of Indemnity Relating To Pension Obligations Proceeds from contributions from parent Proceeds from Contributions from Parent Payment made in related party transaction Related Party Transaction, Payment Made Related Party Transaction, Payment Made Related party transaction, related deferred tax liabilities transferred Related Party Transaction, Related Deferred Tax Liabilities Transferred Related Party Transaction, Related Deferred Tax Liabilities Transferred Derivative [Table] Derivative [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Equity swaps and options Equity Swaps And Options [Member] Equity Swaps And Options [Member] Credit default swaps Credit Default Swap [Member] Total return swaps Total Return Swap [Member] Foreign currency forwards, swaps and options Foreign Currency Forwards Swaps And Options [Member] Foreign currency forwards swaps and options. Fixed income forwards Fixed Income Forward Contracts [Member] Fixed Income Forward Contracts [Member] Interest rate swaps, options and forwards Interest Rate Swaps, Options and Forwards [Member] Interest Rate Swaps, Options and Forwards [Member] Derivative [Line Items] Derivative [Line Items] OTC derivative assets having maturity period of 0 to 12 months Otc Derivative Assets Having Maturity Period Of Zero To Twelve Months Over the counter derivative assets having maturity period of zero to twelve months. OTC derivative assets having maturity period of 1 to 5 years Otc Derivative Assets Having Maturity Period Of One To Five Years OTC derivative assets having maturity period of 1 to5 years. OTC derivative assets having maturity period of greater than 5 years Otc Derivative Assets Having Maturity Period Of Greater Than Five Years OTC derivative assets having maturity period of greater than five years. OTC derivative assets cross-maturity netting Otc Derivative Assets Cross Maturity Netting OTC derivative assets cross maturity netting. Total OTC derivative assets, net of cross-maturity netting Consolidated Otc Derivative Assets, Net Of Cross-Maturity Netting Total OTC derivative assets, net of cross-maturity netting. Cross product counterparty netting Derivative Assets Cross Product Counterparty Netting Derivative Assets Cross Product Counterparty Netting. OTC derivative liabilities having maturity period of 0 to 12 months Otc Derivative Liabilities Having Maturity Period Of Zero To Twelve Months OTC derivative liabilities having maturity period of zero to twelve months. OTC derivative liabilities having maturity period of 1 to 5 years Otc Derivative Liabilities Having Maturity Period Of One To Five Years OTC derivative liabilities having maturity period of 1 to 5 years. OTC derivative liabilities having maturity period of greater than 5 years Otc Derivative Liabilities Having Maturity Period Of Greater Than Five Years OTC derivative liabilities having maturity period of greater than 5 years. OTC derivative liabilities cross-maturity netting Otc Derivative Liabilities Cross Maturity Netting OTC derivative liabilities cross maturity netting. Total OTC derivative liabilities, net of cross-maturity netting Consolidated Otc Derivative Liabilities Net Of Cross Maturity Netting Total OTC derivative liabilities, net of cross-maturity netting. Cross product counterparty netting Derivative Liabilities Cross Product Counterparty Netting Derivative Liabilities Cross Product Counterparty Netting Total OTC derivative liabilities included in Financial instruments sold, not yet purchased Otc Derivative Liabilities Included In Financial Instruments Sold Not Yet Purchased OTC Derivative Liabilities Included In Financial Instruments Sold Not Yet Purchased. Exchange traded derivative assets Exchange Traded Derivative Assets Fair value of exchange traded derivative assets. Cash collateral received Cash Collateral Received Cash collateral received that was netted against OTC derivative assets. Exchange traded derivative liabilities, with fair value Exchange Traded Derivative Liabilities Fair value of exchange traded derivative liabilities. Cash collateral pledged Cash Collateral Pledge Cash collateral pledged that was netted against OTC derivative liabilities. Agency mortgage-backed securities Mortgage And Asset Backed Securitization Activity Agency [Member] Mortgage and asset backed securitization activity agency. Non-agency mortgage and other asset-backed securities Mortgage And Asset Backed Securitization Activity Non Agency [Member] Mortgage and asset backed securitization activity non agency. JCP Entities JCP Entities [Member] JCP Entities [Member] Equity investments Equity Commitments Committed equity capitalization. Funded equity commitments Funded Equity Commitments Funded amount of the committed equity capitalization at the balance sheet date. Carrying amount of equity investment Carrying Amount Of Equity Investments Carrying amount of equity investments. Carrying amount Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Non-exchange-traded securities Non Exchange Traded Securities [Member] Non-exchange traded securities. CDOs and CLOs Collateralized Debt Obligations and Collateralized Loan Obligations [Member] Collateralized Debt Obligations and Collateralized Loan Obligations [Member] RMBS Residential Mortgage Backed Securities [Member] CMBS Commercial Mortgage Backed Securities [Member] Other ABS Other Asset Backed Securities [Member] Other asset-backed securities. Loans and other receivables Derivatives Investments at fair value Investments At Fair Value [Member] Investments At Fair Value [Member] Private equity securities Private Equity Securities [Member] Private equity securities. Total return swaps Equity options Equity Option [Member] Interest rate swaps Interest Rate Swap [Member] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Discounted cash flows Discounted Cash Flow Approach [Member] Discounted Cash Flow Approach [Member] Scenario analysis Scenario Analysis [Member] Scenario Analysis [Member] Market approach Valuation, Market Approach [Member] Option model/default rate Option Model/Default Rate Valuation Technique [Member] Option Model/Default Rate Valuation Technique [Member] Volatility benchmarking Volatility Benchmarking [Member] Volatility Benchmarking [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Price Measurement Input, Offered Price [Member] Basis points Measurement Input, Basis Points [Member] Measurement Input, Basis Points [Member] Transaction level Measurement Input, Transaction Level [Member] Measurement Input, Transaction Level [Member] Underlying stock price Measurement Input, Share Price [Member] Estimated recovery percentage Measurement Input, Estimated Recovery Percentage [Member] Measurement Input, Estimated Recovery Percentage [Member] Discount rate/yield Measurement Input, Discount Rate [Member] Constant prepayment rate Measurement Input, Prepayment Rate [Member] Constant default rate Measurement Input, Default Rate [Member] Loss severity Measurement Input, Loss Severity [Member] Cumulative loss rate Measurement Input, Cumulative Loss Rate [Member] Measurement Input, Cumulative Loss Rate [Member] Revenue growth Measurement Input, Long-term Revenue Growth Rate [Member] Volatility Measurement Input, Price Volatility [Member] Default probability Measurement Input, Default Probability [Member] Measurement Input, Default Probability [Member] Weighted Average Weighted Average [Member] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Derivative assets Derivative Asset Financial instruments sold, not yet purchased, at fair value Derivative liabilities Derivative Liability Financial instruments owned, measurement input Financial Instruments, Owned, Measurement Input Financial Instruments, Owned, Measurement Input Financial instruments owned, measurement input, term Financial Instruments, Owned, Measurement Input, Term Financial Instruments, Owned, Measurement Input, Term Financial instruments sold, not yet purchased, measurement input Financial Instruments Sold, Not Yet Purchased, Measurement Input Financial Instruments Sold, Not Yet Purchased, Measurement Input Derivative asset, measurement input Derivative Asset, Measurement Input Derivative liability, measurement input Derivative Liability, Measurement Input Value of asset excluded from significant unobservable inputs Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Asset Exclusion Value Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Asset Exclusion Value Value of liability excluded from significant unobservable inputs Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Exclusion Value Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Exclusion Value Commitments, Contingencies and Guarantees Commitments Contingencies and Guarantees [Text Block] Investments at fair value Investments [Member] Structured notes Structured Notes [Member] Structured Notes [Member] Net derivatives US Treasury securities US Treasury Securities [Member] Level 1 Fair Value, Inputs, Level 1 [Member] Transfers of assets from Level 2 to Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers of assets from Level 3 to Level 2 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Transfers of liabilities from Level 2 to Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 Transfers of liabilities from Level 3 to Level 2 Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3 Net gains/(losses) on Level 3 assets (realized and unrealized) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Net gains/(losses) on Level 3 liabilities (realized and unrealized) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Aggregate fair value of loans and other receivables on nonaccrual status and/or 90 days or greater past due Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status Loans and other receivables greater than 90 days past due Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due Cash and securities segregated and on deposit for regulatory purposes with clearing and depository organizations Cash and Securities Segregated under Federal and Other Regulations Accounting Changes and Error Corrections [Abstract] Accounting Developments New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Securitization Vehicles Securitization Activity [Member] Securitization Activity [Member] Other Other Activity [Member] Other activity. Cash Cash [Member] Financial instruments owned Financial Instruments Owned [Member] Financial Instruments Owned [Member] Securities purchased under agreement to resell Securities Purchased Under Agreement [Member] Securities Purchased Under Agreement [Member] Other secured financings Other Secured Financings [Member] Other Secured Financings [Member] Other liabilities Other Liabilities [Member] Assets Variable Interest Entity, Consolidated, Carrying Amount, Assets Liabilities Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Secured financing included in inventory and eliminated Vie Secured Financing Eliminated In Consolidation Secured financing held by The Company in Inventory and eliminated in consolidation. Schedule of Collateralized Financing Transactions Schedule of Collateralized Financing Transactions [Table Text Block] Schedule of Collateralized Financing Transactions [Table Text Block] Summary of Repurchase Agreements and Securities Borrowing and Lending Arrangements Offsetting Assets and Liabilities [Table Text Block] Offsetting Assets and Liabilities [Table Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Equity Method Investee Equity Method Investee [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Equity Investments in Jefferies Capital Partners Related Funds Equity Investments in Jefferies Capital Partners Related Funds [Member] Equity Investments in Jefferies Capital Partners Related Funds [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Equity investments loans in related funds Equity Investments Loans In Related Funds Equity investments in and loans to related funds, in aggregate. Other revenues and investment income (loss) Other Revenues And Investment Income Loss On Private Equity Related Investments Other Revenues And Investment Income Loss On Private Equity Related Investments Service charges Related Party Transaction, Other Revenues from Transactions with Related Party Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Goodwill, Beginning Balance Goodwill Translation adjustments Goodwill, Foreign Currency Translation Gain (Loss) Goodwill, Ending Balance Investments Investment [Text Block] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Interest rate swaps Derivative Financial Instruments, Assets [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Interest rate contracts Interest Rate Contract [Member] Foreign exchange contracts Foreign Exchange Contract [Member] Equity contracts Equity Contract [Member] Commodity contracts Commodity Contract [Member] Credit contracts Credit Risk Contract [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Gains (losses) recognized in interest expense on fair value hedge Gain (Loss) on Fair Value Hedges Recognized in Earnings Unrealized and realized gains (losses) Gain (Loss) on Derivative Instruments, Net, Pretax Summary of Long-Term Debt Carrying Values Including Unamortized Discounts and Premiums Schedule of Long-term Debt Instruments [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net earnings (loss) Adjustments to reconcile net earnings (loss) to net cash used in operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Income on loans to and investments in related parties Income On Loans To And Investments In Related Parties Income On Loans To And Investments In Related Parties Distributions received on investments in related parties Distributions Received On Investments In Related Parties Distributions Received On Investments In Related Parties Other adjustments Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Net change in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Securities deposited with clearing and depository organizations (Decrease) Increase In Cash And Securities Segregated And On Deposit For Regulatory Purposes Or Deposited With Clearing And Depository Organizations The net change during the reporting period of the amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances and cash and securities segregated in compliance with regulations. Receivables: Increase (Decrease) in Receivables [Abstract] Brokers, dealers and clearing organizations Increase (Decrease) in Receivables from Brokers-Dealers and Clearing Organizations Customers Increase Decrease In Customers Receivable The net change during the reporting period of the amounts due from customers for fees and charges arising from transactions related to the entity's brokerage activities and operations. Fees, interest and other Increase (Decrease) in Other Receivables Securities borrowed Increase (Decrease) in Securities Borrowed Financial instruments owned Increase (Decrease) in Financial Instruments Used in Operating Activities Securities purchased under agreements to resell Increase (Decrease) in Receivables under Repurchase Agreements Other assets Increase (Decrease) in Other Operating Assets Payables: Increase (Decrease) in Operating Liabilities [Abstract] Brokers, dealers and clearing organizations Increase (Decrease) in Payables to Broker-Dealers and Clearing Organizations Customers Increase (Decrease) in Payables to Customers Securities loaned Increase (Decrease) in Securities Loaned Transactions Financial instruments sold, not yet purchased Increase (Decrease) in Financial Instruments Sold, Not yet Purchased Securities sold under agreements to repurchase Increase (Decrease) in Payables under Repurchase Agreements Accrued expenses and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Contributions to loans to and investments in related parties Payments to Fund Long-term Loans to Related Parties Distributions from loans to and investments in related parties Proceeds from Collection of Long-term Loans to Related Parties Net payments on premises and equipment Payments to Acquire Property, Plant, and Equipment Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from short-term borrowings Proceeds from Short-term Debt Payments on short-term borrowings Repayments of Short-term Debt Proceeds from issuance of long-term debt, net of issuance costs Proceeds from Issuance of Senior Long-term Debt Repayment of long-term debt Repayments of Long-term Debt Dividend distribution Payments of Dividends Net proceeds from (payments on) other secured financings Proceeds from (Payments for) Other Financing Activities Net change in bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Proceeds from contributions of noncontrolling interests Proceeds from Noncontrolling Interests Payments on distributions to noncontrolling interests Payments to Noncontrolling Interests Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash and Cash Equivalents Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid (received) during the period for: Cash Paid Received During Period [Abstract] Cash paid (received) during the period for: Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Income taxes, net Income Taxes Paid, Net Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 4.850% Senior Notes Four Point Eight Five Percentage Senior Notes, Due 2027 [Member] Four Point Eight Five Percentage Senior Notes, Due 2027 [Member] 3.875% Convertible Senior Debentures Three Point Eight Seven Five Percentage Convertible Senior Debentures Due Two Thousand Twenty Nine [Member] 3.875% Convertible Senior Debentures, due, 2029. 8.500% Senior Notes Eight Point Five Percentage Senior Notes Due Two Thousand Nineteen [Member] 8.5% Senior Notes, due 2019. 4.150% Senior Notes Four Point One Five Zero Percent Senior Notes Due 2030 [Member] Four Point One Five Zero Percent Senior Notes Due 2030 [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Debt Unsecured Debt [Member] Secured Debt Secured Debt [Member] Increase (decrease) of long-term debt Increase (Decrease) of Long-term Debt Increase (Decrease) of Long-term Debt Repayments of debt Repayments of Debt Debt instrument interest rate Debt Instrument, Interest Rate, Stated Percentage Long-term debt Long-term Debt Redemption price as percentage of principal amount redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Exchange-traded Exchange Traded Options [Member] Cleared OTC Otc Cleared [Member] OTC Cleared [Member] Bilateral OTC Bilateral Otc [Member] Bilateral OTC [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Fair Value, Assets Derivative Asset, Fair Value, Gross Asset Number of Contracts, Assets Derivative Asset, Number of Instruments Held Fair Value, Liabilities Derivative Liability, Fair Value, Gross Liability Number of Contracts, Liabilities Derivative Liability, Number of Instruments Held Amounts offset in the Consolidated Statements of Financial Condition, Assets Derivative Asset, Fair Value, Amount Offset Against Collateral Amounts offset in the Consolidated Statements of Financial Condition, Liabilities Derivative Liability, Fair Value, Amount Offset Against Collateral Net amounts per Consolidated Statements of Financial Condition, Assets Financial Instruments, Owned, Derivatives and Other Contractual Agreements, at Fair Value Net amounts per Consolidated Statements of Financial Condition, Liabilities Financial Instruments Sold, Not yet Purchased, Derivatives and Other Contracts Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair value of securities received as collateral Fair Value of Securities Received as Collateral that Can be Resold or Repledged Cash and securities segregated and on deposit for regulatory purposes or deposited with clearing and depository organizations Aggregate amortization expense Amortization of Intangible Assets Estimated future amortization expense Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Remainder of fiscal 2019 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Year ending November 30, 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two Year ending November 30, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three Year ending November 30, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four Year ending November 30, 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five Net gains (losses) from our investments in JCP Fund V Unrealized Gain (Loss) on Securities Net increase (decrease) in net assets resulting from operations Equity Method Investment, Increase (Decrease) in Net Assets Resulting from Operations Equity Method Investment, Increase (Decrease) in Net Assets Resulting from Operations Revenue related to performance obligations satisfied Contract With Customer, Performance Obligation Satisfied Contract With Customer, Performance Obligation Satisfied Revenue associated with distribution services, a portion of which related to prior periods Contract with Customer, Performance Obligation Satisfied in Previous Period Receivables related to revenue from contracts with customers Contract with Customer, Asset, Net Deferred revenue Contract with Customer, Liability, Current Deferred revenue, revenue recognized Contract with Customer, Liability, Revenue Recognized Capitalized contract cost Capitalized Contract Cost, Net Expenses related to capitalized costs to fulfill a contract Capitalized Contract Cost, Amortization Unrecognized tax benefits Unrecognized Tax Benefits Unrecognized tax benefits that would impact effective tax rate in future Unrecognized Tax Benefits that Would Impact Effective Tax Rate Accrued interest on unrecognized tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Accrued penalties on unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties Accrued Increase of provisional tax charge related to the Tax Act during period Tax Cuts And Jobs Act Of 2017, Measurement Period Adjustment, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Measurement Period Adjustment, Provisional Income Tax Expense (Benefit) Total tax charge related to Tax Act Tax Cuts And Jobs Act Of 2017, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Provisional Income Tax Expense (Benefit) Total tax charge related to write down of deferred tax asset as a result of the Tax Act Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense (Benefit) Income tax expense Income Tax Expense (Benefit) Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Collateralized Transactions Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block] Statement of Financial Position [Abstract] Variable Interest Entities Variable Interest Entities [Member] Variable Interest Entities [Member] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Pledged financial instruments Pledged Financial Instruments, Not Separately Reported, Securities Other assets Other Assets Other secured financings Other Secured Financings Accrued expenses and other liabilities Accounts Payable and Accrued Liabilities Long-term debt at fair value Long-term Debt, Fair Value Brokers and Dealers [Abstract] Net Capital Requirements Regulatory Capital Requirements Disclosure [Text Block] Regulatory capital requirements disclosure. Fair Value Disclosures Fair Value Disclosures [Text Block] Short-Term Borrowings Short-term Debt [Text Block] Assets and Liabilities of Consolidated VIEs Prior to Consolidation Variable Interest Entities Primary Beneficiary [Table Text Block] Variable Interest Entities Primary Beneficiary [Table Text Block] Variable Interests in Non-Consolidated Variable Interest Entities Non Consolidated Variable Interest Entities [Table Text Block] Non-consolidated variable interest entities aggregated by principal business activity. Loss Contingencies [Table] Loss Contingencies [Table] Jefferies Capital Partners LLC Jefferies Capital Partners Llc [Member] Jefferies capital partners, LLC. Other Investments Investments, Other [Member] Investments, Other [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Standby Letters of Credit Standby Letters of Credit [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Outstanding equity commitments Loan commitments outstanding to clients Loan Commitments Outstanding Loan commitments outstanding to clients. Fair value of derivative contracts approximated deemed to meet the definition of a guarantee Guarantee Obligations Maximum Exposure Fair Value Guarantee obligations maximum exposure fair value. Letters of credit commitments Standby Letters Of Credit Commitments Standby Letters Of Credit Commitments Standby letters of credit expiration period Standby Letters of Credit Expiration Period Standby Letters of Credit Expiration Period Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Table] Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Table] Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer relationships Customer Relationships [Member] Trade name Trade Names [Member] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Exchange and clearing organization membership interests and registrations Exchange And Clearing Organization Membership Interests And Registrations [Member] Exchange and clearing organization membership interests and registrations. Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Line Items] Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Line Items] [Line Items] for Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Table] Goodwill Gross costs - finite lived intangible assets Finite-Lived Intangible Assets, Gross Gross costs - indefinite lived intangible assets Indefinite Lived Intangible Assets Gross Indefinite lived Intangible asset Gross (before impairment). Total gross costs - intangible assets Intangible Assets, Gross (Excluding Goodwill) Accumulated amortization - finite lived intangible assets Finite-Lived Intangible Assets, Accumulated Amortization Net carrying amount - finite lived intangible assets Finite-Lived Intangible Assets, Net Net carrying amount - indefinite lived intangible assets Indefinite Lived Intangible Asset Net Cost (After Impairment) Indefinite Lived Intangible Asset Net Cost (After Impairment) Total net carrying amount - intangible assets Intangible Assets, Net (Excluding Goodwill) Weighted average remaining lives (years) Finite-Lived Intangible Asset, Useful Life Net derivatives Derivative Financial Instruments, Liabilities [Member] Assets: Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Total gains/losses (realized and unrealized) Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances Net transfers into/ (out of) Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Ending Balance Change in unrealized gains/(losses) included in earnings for instruments still held Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held Fair Value, Assets Measured On Recurring Basis, Change In Unrealized Gain (Loss) Included In Other Comprehensive Income Fair Value, Assets Measured On Recurring Basis, Change In Unrealized Gain (Loss) Included In Other Comprehensive Income Liabilities: Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Total gains/losses (realized and unrealized) Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances Net transfers into/ (out of) Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net Ending Balance Change in unrealized gains/(losses) included in earnings for to instruments still held Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Change in unrealized gains/(losses) included in other comprehensive income for instruments still held Fair Value, Liabilities Measured On Recurring Basis, Change In Unrealized Gain (Loss) Included In Other Comprehensive Income Fair Value, Liabilities Measured On Recurring Basis, Change In Unrealized Gain (Loss) Included In Other Comprehensive Income Transfers and Servicing [Abstract] Transferred assets Assets Transferred Due To Securitization Assets transferred due to securitization activities in which the Company had continuing involvement. Proceeds on new securitizations Proceeds On New Securitizations Proceeds On New Securitizations Cash flows received on retained interests Cash Flows Between Transferor and Transferee, Proceeds from New Transfers Income Statement [Abstract] Commissions and other fees Brokerage Commissions Revenue Principal transactions Principal Transactions Revenue, Net Investment banking Investment Banking Revenue Asset management fees Asset Management Fees And Investment Income Loss From Managed Funds Revenues earned from management, administrative and performance fees from funds managed by the firm, third-party managed funds, and investment income (loss) from investments in these funds. Interest Interest Income, Operating Other Other Operating Income (Expense), Net Total revenues Interest expense Interest Expense Net revenues Non-interest expenses: Noninterest Expense [Abstract] Compensation and benefits Labor and Related Expense Non-compensation expenses: Non Labor and Related Expense [Abstract] Non Labor and Related Expense [Abstract] Floor brokerage and clearing fees Floor Brokerage, Exchange and Clearance Fees Technology and communications Communications and Information Technology Occupancy and equipment rental Occupancy, Net Business development Business Development Professional services Professional Fees Underwriting costs Underwriting Costs Underwriting Costs Other Other Expenses Total non-compensation expenses Non Compensation Expenses Non Compensation Expenses Total non-interest expenses Earnings before income taxes Net earnings (loss) Net earnings (loss) attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net earnings (loss) attributable to Jefferies Group LLC Net Income (Loss) Attributable to Parent Earliest Tax Year Subject to Examination in the Major Tax Jurisdictions in which the Company Operates Summary of Income Tax Examinations [Table Text Block] Net Revenues, Expenses and Total Assets by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Net Revenues by Geographic Region Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Level 2 Fair Value, Inputs, Level 2 [Member] Fair value based on net asset value Fair Value Measured at Net Asset Value Per Share [Member] U.S. government and federal agency securities US Treasury and Government [Member] Sovereign obligations Sovereign Debt Securities [Member] Residential mortgage-backed securities Commercial mortgage-backed securities Other asset-backed securities Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Alternative investment Assets: Fair Value Assets Measured On Recurring Basis [Abstract] Fair value assets measured on recurring basis. Financial instruments owned, excluding Investments at fair value based on NAV Financial Instruments, Owned, at Fair Value Excluding Investments at Net Asset Value Financial Instruments, Owned, at Fair Value Excluding Investments at Net Asset Value Counterparty and Cash Collateral Netting Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset Liabilities: Fair Value Liabilities Measured On Recurring Basis [Abstract] Fair value liabilities measured on recurring basis. Financial instruments sold, not yet purchased: Counterparty and Cash Collateral Netting Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Long-term debt External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Domain] External Credit Rating by Grouping [Domain] Investment Grade External Credit Rating, Investment Grade [Member] Non-investment Grade External Credit Rating, Non Investment Grade [Member] Unrated Unrated [Member] Unrated [Member] Credit Derivatives Contract Type [Axis] Credit Derivatives Contract Type [Axis] Credit Derivatives Contract Type [Domain] Credit Derivatives Contract Type [Domain] Index credit default swaps Credit Index Product [Member] Single name credit default swaps Credit Default Swaption [Member] Total Notional Derivative, Notional Amount Interest income Investments in and Advances to Affiliates, Dividend or Interest Credited to Income Unfunded commitment fees Line of Credit Facility, Unfunded Commitment Fee Income Line of Credit Facility, Unfunded Commitment Fee Income Origination and syndication fee revenues Fees Earned To Joint Venture Related To Loan Origination Fees paid to joint venture related to loan origination. Origination fee expenses Fees Paid To Joint Venture Related To Loan Origination Fees paid to joint venture related to loan origination. CLO placement fee revenues Derivative losses Derivative, Gain (Loss) on Derivative, Net Underwriting fees Underwriting Fees Underwriting Fees Service fees Service Fees Earned Service Fees Earned Restricted cash awards Deferred Compensation Arrangement with Individual, Compensation Expense Restricted stock and RSUs Share-based Compensation Profit sharing plan Compensation Cost Related To Profit Sharing Plan Compensation cost related to profit sharing plan. Total compensation cost Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost Consolidation Consolidation, Policy [Policy Text Block] Accounting Standards to be Adopted in Future Periods and Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Revenues recognition Revenue from Contract with Customer [Policy Text Block] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Director Director [Member] Hedge Fund Managed By Jefferies Hedge Fund Managed By Jefferies Financial Group Inc. [Member] Hedge Fund Managed By Jefferies Financial Group Inc. [Member] Commissions and other fees Capital Markets And Asset Management Services, Commissions And Other Fees [Member] Capital Markets And Asset Management Services, Commissions And Other Fees [Member] Principal transactions Capital Markets And Asset Management Services, Principal Transactions [Member] Capital Markets And Asset Management Services, Principal Transactions [Member] Other revenues Capital Markets And Asset Management Services, Other [Member] Capital Markets And Asset Management Services, Other [Member] Accrued expenses and other liabilities Accounts Payable and Accrued Liabilities [Member] Charges to Jefferies for services provided Revenue from Related Parties Charges from Jefferies for services received Related Party Transaction, Expenses from Transactions with Related Party Receivable from Jefferies Accounts Receivable, Related Parties, Current Payable to Jefferies Accounts Payable, Related Parties, Current Distribution to affiliates, approved amount Due to Affiliate Payments of distributions to affiliates Payments of Distributions to Affiliates Distribution payable accrued during period Increase (Decrease) in Due to Affiliates Net current tax receivable Tax Receivable, Related Parties, Current Tax Receivable, Related Parties, Current Net current tax payable Tax Payable, Related Parties, Current Tax Payable, Related Parties, Current Payment made to related party related to tax sharing agreement Related Party Transaction, Payment Made Related To Tax Sharing Agreement Related Party Transaction, Payment Made Related To Tax Sharing Agreement Payments to acquire investments Payments to Acquire Investments Net gain (loss) on investments Related Party Transaction, Gain (Loss) on Transaction Related Party Transaction, Gain (Loss) on Transaction Payables-brokers, dealers and clearing organizations Investment in related party Related Party Transaction, Investment Amount Related Party Transaction, Investment Amount Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income (loss) attributable to Jefferies Group LLC Comprehensive Income (Loss), Net of Tax, Attributable to Parent Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Derivative instrument liabilities with credit-risk-related contingent features Derivative, Net Liability Position, Aggregate Fair Value Collateral posted Collateral Already Posted, Aggregate Fair Value Collateral received Collateral Received, Aggregate Fair Value Collateral Received, Aggregate Fair Value Return of and additional collateral required in the event of a credit rating downgrade below investment grade Additional Collateral Required In The Event Of Credit Rating Downgrade, Aggregate Fair Value Additional Collateral Required In The Event Of Credit Rating Downgrade, Aggregate Fair Value Summary of Interest Income, Other Revenues and Investment Income Attributable to Related Party Private Equity Funds Interest and Other Income [Table Text Block] Schedule of related party transactions Schedule of Related Party Transactions [Table Text Block] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Debt Securities, Trading, and Equity Securities, FV-NI [Table] U.S. government agency RMBS Us Government Agency Issued Rmbs [Member] Us Government Agency Issued Rmbs [Member] U.S. government agency CMBS Us Government Agency Issued Cmbs [Member] Us Government Agency Issued Cmbs [Member] Consumer and other loans Other Debt Obligations [Member] Debt and Equity Securities, FV-NI [Line Items] Debt and Equity Securities, FV-NI [Line Items] Total RMBS securitization assets Rmbs Securitization Assets Represents unpaid principal amount of assets in residential mortgage backed securitization vehicles at the balance sheet date. Total CMBS securitization assets Cmbs Securitization Assets Represents unpaid principal amount of assets in commercial mortgage backed securitization vehicles at the balance sheet date. Total Collateralized loan obligations Collateralized Loan Obligations Securitization Assets Collateralized Loan Obligations Securitization Assets Consumer and other loans Other Securitization Assets Other Securitization Assets Retained Interests Retained Interest, Fair Value Disclosure Schedule of Goodwill Schedule of Goodwill [Table Text Block] Summary of Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Future Amortization Expense Related to Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Loans outstanding to certain employees Loans and Leases Receivable, Related Parties Securities or Other Assets Sold under Agreements to Repurchase, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Assets Sold under Agreements to Repurchase, Maturity Period [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Overnight and Continuous Maturity Overnight [Member] Up to 30 Days Maturity Less than 30 Days [Member] 31-90 Days Maturity 30 to 90 Days [Member] Greater than 90 Days Maturity Greater than 90 Days [Member] Activity Related to Securitizations Accounted for as Sales Summary Of Securitization Arrangements Activity [Table Text Block] Tabular disclosure of the amount of financial assets securitized, proceeds and net revenues and cash flows received from retained interests. Summary of Retained Interests in SPEs Securitization Activities And Variable Interest Entity Table [Table Text Block] Total information regarding securitization vehicles to which Jefferies, acting as transferor, have transferred assets and for which the Company received sale accounting treatment. Net Capital Requirements [Table] Net Capital Requirements [Table] Net Capital Requirements [Table] Jefferies LLC Jefferies [Member] A registered broker dealer under the Securities and Exchange act of 1934 and a wholly owned subsidiary of the Parent (Jefferies). Net Capital Requirements [Line Items] Net Capital Requirements [Line Items] Net Capital Requirements [Line Items] Net Capital Net Capital Excess Net Capital Alternative Excess Net Capital Securities borrowing arrangements Securities Borrowed [Abstract] Gross Amounts Securities Borrowed, Gross Netting in Consolidated Statement of Financial Condition Securities Borrowed, Liability Net Amounts in Consolidated Statement of Financial Condition Securities Borrowed Additional Amounts Available for Setoff Securities Borrowed, Collateral, Obligation to Return Cash Available Collateral Securities Borrowed, Collateral, Obligation to Return Securities Net Amount Securities Borrowed, Amount Offset Against Collateral Reverse repurchase agreements Offsetting Securities Purchased under Agreements to Resell [Abstract] Gross Amounts Securities Purchased under Agreements to Resell, Gross Netting in Consolidated Statement of Financial Condition Securities Purchased under Agreements to Resell, Liability Net Amounts in Consolidated Statement of Financial Condition Securities Purchased under Agreements to Resell Additional Amounts Available for Setoff Securities Purchased under Agreements to Resell, Not Offset, Policy Election Deduction Available Collateral Securities Purchased under Agreements to Resell, Fair Value of Collateral Net Amount Securities Purchased under Agreements to Resell, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election Securities lending arrangements Securities Loaned [Abstract] Gross Amounts Securities Loaned, Gross Netting in Consolidated Statement of Financial Condition Securities Loaned, Asset Net Amounts in Consolidated Statement of Financial Condition Securities Loaned Additional Amounts Available for Setoff Securities Loaned, Collateral, Right to Reclaim Cash Available Collateral Securities Loaned, Collateral, Right to Reclaim Securities Net Amount Securities Loaned, Amount Offset Against Collateral Repurchase agreements Offsetting Securities Sold under Agreements to Repurchase [Abstract] Gross Amounts Securities Sold under Agreements to Repurchase, Gross Netting in Consolidated Statement of Financial Condition Securities Sold under Agreements to Repurchase, Asset Net Amounts in Consolidated Statement of Financial Condition Securities Sold under Agreements to Repurchase Additional Amounts Available for Setoff Securities Sold under Agreements to Repurchase, Not Offset, Policy Election Deduction Available Collateral Securities Sold under Agreements to Repurchase, Fair Value of Collateral Net Amount Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral Securities borrowing arrangements Collateralized Financing Transactions Securities Borrowing Arrangements Collateralized Financing Transactions Securities Borrowing Arrangements Securities borrowing arrangements, collateral Collateralized Financing Transactions Securities Borrowing Arrangements Collateral Collateralized Financing Transactions Securities Borrowing Arrangements Securities Collateral Received Securities borrowing arrangements, repurchase agreements Collateralized Financing Transactions Securities Borrowing Arrangements Repurchase Agreements Collateralized Financing Transactions Securities Borrowing Arrangements Repurchase Agreements Securities borrowing arrangements, repurchase agreements, pledged securities collateral Collateralized Financing Transactions Securities Borrowing Arrangements Pledged Securities Collateral Collateralized Financing Transactions Securities Borrowing Arrangements Pledged Securities Collateral Schedule of Components of Compensation Cost Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Schedule of Remaining Unamortized Amounts Related to Certain Compensation Plans Schedule Of Share Based Compensation Allocation Of Period Costs And Amortization Period Table [Table Text Block] Schedule Of Share Based Compensation Allocation Of Period Costs And Amortization Period Table [Table Text Block] Revenues from Contracts with Customers Revenue from Contract with Customer [Text Block]