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] 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 [Member] Maturity Overnight [Member] Up to 30 Days [Member] Maturity Less than 30 Days [Member] 30-90 Days [Member] Maturity 30 to 90 Days [Member] Greater than 90 Days [Member] Maturity Greater than 90 Days [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 Segment Reporting [Abstract] Segment Reporting Segment Reporting Disclosure [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 Cash and Securities Segregated under Federal and Other Regulations Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Other Commitments [Table] Other Commitments [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Equity commitments [Member] Equity Commitments [Member] Equity commitments. Loan commitments [Member] Loan Commitments [Member] Loan commitments. Mortgage-related and other purchase commitments [Member] Mortgage Related Commitments [Member] Mortgage-related commitments. Underwriting commitments [Member] Underwriting Commitments [Member] Underwriting Commitments [Member] Forward starting reverse repos [Member] Forward Starting Reverse Repos [Member] Forward Starting Reverse Repos [Member] Forward starting repos [Member] Forward Starting Repos [Member] Forward Starting Repos [Member] Other unfunded commitments [Member] Other Commitments [Member] Other Commitments [Member] Other Commitments [Line Items] Other Commitments [Line Items] 2017 Commitments And Guarantees Expected To Be Due Current Commitments and guarantees with a remaining term that matures during the fiscal year. These may include, equity, loan, mortgage-related and underwriting commitments, derivative guarantees, etc. 2018 Commitments And Guarantees Expected To Be Due In Two Years Commitments and guarantees expected to be due within 2 fiscal years. These may include, equity, loan, mortgage-related and underwriting commitments, derivative guarantees, etc. 2019 and 2020 Commitments And Guarantees Expected To Be Due In Three And Four Years Commitments and guarantees expected to be due within 3 to 4 fiscal years. These may include, equity, loan, mortgage-related and underwriting commitments, derivative guarantees, etc. 2021 and 2022 Commitments And Guarantees Expected To Be Due In Five And Six Years Commitments and guarantees expected to be due within 5 to 6 fiscal years. These may include, equity, loan, mortgage-related and underwriting commitments, derivative guarantees, etc. 2023 and Later Commitments And Guarantees Expected To Be Due Thereafter Commitments and guarantees expected to be due within 7 fiscal years and thereafter. These may include, equity, loan, mortgage-related and underwriting commitments and derivative guarantees, etc. Notional/ Maximum Payout Guarantor Obligations, Maximum Exposure, Undiscounted Guarantor obligation settled amount Guarantor Obligation Settled Amount Guarantor Obligation Settled Amount Guarantor obligation settled period (in days) Guarantor Obligation Settled Period Guarantor Obligation Settled Period Schedule of Credit Derivatives [Table] Schedule of Credit Derivatives [Table] Credit Rating, Standard & Poor's [Axis] Credit Rating, Standard & Poor's [Axis] External Credit Rating, Standard & Poor's [Domain] External Credit Rating, Standard & Poor's [Domain] AAA/Aaa [Member] Standard & Poor's, AAA Rating [Member] AA/Aa [Member] Standard & Poor's, AA Rating [Member] A [Member] Standard & Poor's, A Rating [Member] BBB/Baa [Member] Standard & Poor's, BBB Rating [Member] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Domain] External Credit Rating by Grouping [Domain] Below Investment Grade [Member] External Credit Rating, Non Investment Grade [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 [Member] Credit Index Product [Member] Single name credit default swaps [Member] Single Name Credit Default Swaps [Member] Single name credit default swaps [Member] Credit Derivatives [Line Items] Credit Derivatives [Line Items] External credit ratings External Credit Ratings For Derivative Contract Credit Credit ratings for derivative contracts in which a significant change in credit quality of the underlying financial instrument may obligate the guarantor to make a payment. Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Capital Markets [Member] Capital Markets [Member] Capital markets. Asset management [Member] Asset Management Income [Member] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Net revenues Revenues, Net of Interest Expense Expenses Noninterest Expense Segment assets Assets Brokers and Dealers [Abstract] Net Capital, Adjusted and Excess Net Capital Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Corporate equity securities [Member] Equity Securities [Member] Corporate debt securities [Member] Corporate Debt Securities [Member] Mortgage- and asset-backed securities [Member] Mortgage and Asset-Backed Securities [Member] Mortgage and Asset-Backed Securities [Member] U.S. government and federal agency securities [Member] US Government Corporations and Agencies Securities [Member] Municipal securities [Member] Municipal Bonds [Member] Sovereign obligations [Member] Sovereign Debt [Member] Loans and other receivables [Member] Loans and Finance Receivables [Member] Income Tax Disclosure [Abstract] Earliest Tax Year Subject to Examination in the Major Tax Jurisdictions in which the Company Operates Summary of Income Tax Examinations [Table Text Block] Transfers and Servicing [Abstract] 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. Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Debt Disclosure [Abstract] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Bank loans [Member] Notes Payable to Banks [Member] Secured revolving loan facilities [Member] Secured Debt [Member] Bank Overdrafts [Member] Bank Overdrafts [Member] Line of Credit [Member] Line of Credit [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Loan Facility [Member] Loan Facility [Member] Loan Facility [Member] First Secured Revolving Loan Facility [Member] First Secured Revolving Loan Facility [Member] First Secured Revolving Loan Facility [Member] Second Secured Revolving Loan Facility [Member] Second Secured Revolving Loan Facility [Member] Second Secured Revolving Loan Facility [Member] Floating rate puttable notes [Member] Puttable Notes [Member] Puttable Notes [Member] Demand Loan Facility [Member] Demand Loan Facility [Member] Demand Loan Facility [Member] Intraday Credit Facility [Member] Intraday Credit Facility [Member] Intraday Credit Facility [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Federal funds effective rate [Member] Federal Funds Effective Swap Rate [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Short-term borrowings Short-term Debt Interest rate on short-term borrowings outstanding Short-term Debt, Weighted Average Interest Rate Average daily short-term borrowings Short-term Debt, Average Outstanding Amount Credit facility maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Net Capital Requirements Regulatory Capital Requirements Disclosure [Text Block] Regulatory capital requirements disclosure. Schedule of Short-term Borrowings Schedule of Short-term Debt [Table Text Block] Compensation Related Costs [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted Cash Awards [Member] Restricted Cash Awards [Member] Restricted Cash Awards [Member] Restricted Stock and RSUs [Member] Restricted Stock and Restricted Stock Units [Member] Restricted Stock and Restricted Stock Units [Member] Compensation Plans [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] 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 Net Capital Requirements [Table] Net Capital Requirements [Table] Net Capital Requirements [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Jefferies [Member] Jefferies [Member] A registered broker dealer under the Securities and Exchange act of 1934 and a wholly owned subsidiary of the Parent (Jefferies). Jefferies Execution [Member] Jefferies Execution [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 Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest rate swaps [Member] Interest Rate Swap [Member] 4.85% Senior Notes, due 2027 [Member] 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 due 2029 [Member] Three Point Eight Seven Five Percentage Convertible Senior Debentures Due Two Thousand Twenty Nine [Member] 3.875% Convertible Senior Debentures, due, 2029. Structured Notes [Member] Structured Notes [Member] Structured Notes [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Debt [Member] Unsecured Debt [Member] Class A Notes, Due 2022 [Member] Class A Notes, Due 2022 [Member] Class A Notes, Due 2022 [Member] Class B Notes, Due 2022 [Member] Class B Notes, Due 2022 [Member] Class B Notes, Due 2022 [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Leucadia [Member] Leucadia [Member] Leucadia. Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent event [Member] Subsequent Event [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt principal amount Debt Instrument, Face Amount Decrease of long-term debt Increase (Decrease) of Long-term Debt Increase (Decrease) of Long-term Debt Long-term debt at fair value Long-term Debt, Fair Value Long-term debt Long-term Debt Senior long-term debt, interest rate Debt Instrument, Interest Rate, Stated Percentage Debenture principal amount Convertible Debenture Principal Amount Principal amount of each Convertible debenture. Debt instrument convertible conversion ratio Debt Instrument, Convertible, Conversion Ratio Conversion price of common stock (dollars per share) Debt Instrument, Convertible, Conversion Price Debt instrument convertible conversion ratio (greater than) Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Earliest period of conversion price Debt Instrument, Convertible, Threshold Trading Days Latest period of conversion price Debt Instrument, Convertible, Threshold Consecutive Trading Days Less than trading price per debenture related to common stock Percentage Of Debt Instrument Convertible Conversion Ratio Percentage of debt instrument convertible conversion ratio. Consecutive trading days Trading Days Consider For Lower Range Of Stock Price Trading days consider for lower range of stock price. Contingent interest Debt Instrument, Convertible, Contingent Interest Debt Instrument, Convertible, Contingent Interest Threshold trading days Debt Instrument, Convertible, Contingent Interest, Threshold Trading Days Debt Instrument, Convertible, Contingent Interest, Threshold Trading Days Interest period Debt Instrument, Convertible, Interest Period Debt Instrument, Convertible, Interest Period Trading price of contingent interest Threshold Trading Price Of Contingent Interest Trading price before accruing contingent interest. Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Futures business [Member] Futures Business [Member] Futures Business [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Earnings (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Non-cash restructuring costs Restructuring Reserve, Settled without Cash Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] KCG Holdings, Inc [Member] KCG Holdings, Inc [Member] KCG Holdings, Inc [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Ownership percentage Equity Method Investment, Ownership Percentage Changes in fair value of investment Unrealized Loss on Securities Net income (loss) in earnings Equity Method Investment, Summarized Financial Information, Net Income (Loss) Securities borrowed Securities Borrowed Securities loaned Securities Loaned 5.125% Senior Notes, due 2018 [Member] Five Point One Two Five Percentage Senior Notes Due Two Thousand Eighteen [Member] 5.125% Senior Notes, due 2018. 8.5% Senior Notes, due 2019 [Member] Eight Point Five Percentage Senior Notes Due Two Thousand Nineteen [Member] 8.5% Senior Notes, due 2019. 2.375% Euro Medium Term Notes, due 2020 [Member] Two Point Three Seven Five Percentage Euro Medium Term Notes Due Two Thousand Twenty [Member] Two Point Three Seven Five Percentage Euro Medium Term Notes Due Two Thousand Twenty [Member] 6.875% Senior Note, due 2021 [Member] Six Point Eight Seven Five Percentage Senior Notes Due Two Thousand Twenty One [Member] 6.875% Senior Note, due 2021. 2.25% Euro Medium Term Notes, due 2022 [Member] Two Point Two Five Percentage Euro Medium Term Notes Due Two Thousand Twenty Two [Member] 2.25 % Euro Medium Term Notes due 2022. 5.125% Senior Notes, due 2023 [Member] Five Point One Two Five Percentage Senior Notes Due Two Thousand Twenty Three [Member] 5.125 % Senior Notes due 2023. 6.45% Senior Debentures, due 2027 [Member] Six Point Four Five Percentage Senior Debentures Due Two Thousand Twenty Seven [Member] 6.45% Senior Debentures due 2027. 6.25% Senior Debentures, due 2036 [Member] Six Point Two Five Percentage Senior Debentures Due Two Thousand Thirty Six [Member] 6.25% Senior Debentures, due 2036. 6.50% Senior Notes, due 2043 [Member] Six Point Five Zero Percentage Senior Notes Due Two Thousand Forty Three [Member] 6.50% Senior Notes due 2043. Debt instrument interest rate Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Financial Instruments Owned and Pledged as Collateral by Type [Axis] Financial Instruments Owned and Pledged as Collateral by Type [Axis] Financial Instruments Owned and Pledged as Collateral, Type [Domain] Financial Instruments Owned and Pledged as Collateral, Type [Domain] RMBS [Member] Residential Mortgage Backed Securities [Member] CMBS [Member] Commercial Mortgage Backed Securities [Member] Other ABS [Member] Other Asset Backed Securities [Member] 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] Assets: Fair Value Assets Measured On Recurring Basis [Abstract] Fair value assets measured on recurring basis. Financial instruments owned: Financial Instruments, Owned, at Fair Value [Abstract] Corporate equity securities Financial Instruments, Owned, Corporate Equities, at Fair Value Corporate debt securities Financial Instruments, Owned, Corporate Debt, at Fair Value CDOs and CLOs Financial Instruments Owned Collateralized Debt Obligations At Fair Value The fair value as of the balance sheet date of firm holdings in structured asset - backed securities whose value and payments are derived from portfolio of fixed income underlying assets. U.S. government and federal agency securities Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value Municipal securities Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value Sovereign obligations Financial Instruments, Owned, Other Sovereign Government Obligations, at Fair Value Mortgage- and asset-backed securities, assets Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value Loans and other receivables Financial Instruments Owned Loans And Other Receivables The fair value as of the balance sheet date of firm holdings in corporate loans, participation certificates in GNMA project and construction loans, and escrow and trade claim receivables. Derivatives Financial Instruments, Owned, Derivatives and Other Contractual Agreements, at Fair Value Investments at fair value Financial Instruments, Owned, Principal Investments, at Fair Value Total 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: Financial Instruments Sold, Not yet Purchased, at Fair Value [Abstract] Corporate equity securities Financial Instruments Sold, Not yet Purchased, Corporate Equities Corporate debt securities Financial Instruments Sold, Not yet Purchased, Corporate Debt U.S. government and federal agency securities Financial Instruments Sold, Not yet Purchased, US Government and Agency Obligations Sovereign obligations Financial Instruments Sold, Not yet Purchased, Other Sovereign Government Debt Loans Fair Value Of Loan Obligations Fair value of loan obligations. Derivatives Financial Instruments Sold, Not yet Purchased, Derivatives and Other Contracts Total financial instruments sold, not yet purchased Financial Instruments Sold, Not yet Purchased, at Fair Value Counterparty and Cash Collateral Netting Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Other secured financings Secured Debt, Other Long-term debt Document And Entity Information [Abstract] Document and Entity Information Abstract. Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Accounting Developments New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Accounting Policies [Abstract] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Adjustments for Error Corrections [Axis] Adjustments for Error Corrections [Axis] Adjustments for Error Correction [Domain] Adjustments for Error Correction [Domain] Classification Error [Member] Classification Error [Member] Classification Error [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Previously Reported [Member] Scenario, Previously Reported [Member] Restatement Adjustment [Member] Restatement Adjustment [Member] Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Net change in 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 Net change in bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [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 [Member] Customer Relationships [Member] Trade Name [Member] Trade Names [Member] Exchange and Clearing Organization Membership Interests and Registrations [Member] Exchange And Clearing Organization Membership Interests And Registrations [Member] Exchange and clearing organization membership interests and registrations. Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] 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) Impairment of intangible assets Impairment of Intangible Assets, Indefinite-lived (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 Fair Value and Related Number of Derivative Contracts Categorized by Type of Derivative Contract Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Unrealized and Realized Gains (Losses) on Derivative Contracts Derivative Instruments, Gain (Loss) [Table Text Block] Remaining Contract Maturity of Fair Value of OTC Derivative Assets and Liabilities Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities Table [Table Text Block] OTC derivatives by risk exposure and maturity profile. Counterparty Credit Quality with Respect to Fair Value of OTC Derivatives Assets Counterparty Credit Quality With Respect To Fair Value Of Otc Derivatives Assets Table [Table Text Block] Counterparty credit quality with respect to the fair value of OTC derivatives assets. Aggregate amortization expense Amortization of Intangible Assets Remainder of fiscal 2017 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Year ended November 30, 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Two Year ended November 30, 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Three Year ended November 30, 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Four Year ended November 30, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Five 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 [Member] Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument [Member] Interest rate contracts [Member] Interest Rate Contract [Member] Foreign exchange contracts [Member] Foreign Exchange Contract [Member] Equity contracts [Member] Equity Contract [Member] Commodity contracts [Member] Commodity Contract [Member] Credit contracts [Member] Credit Risk Contract [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Exchange-traded [Member] Exchange Traded Options [Member] Cleared OTC [Member] Otc Cleared [Member] OTC Cleared [Member] Bilateral OTC [Member] 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 Net amounts per Consolidated Statements of Financial Condition, Liabilities Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] CDOs and CLOs [Member] Collateralized Debt Obligations and Collateralized Loan Obligations [Member] Collateralized Debt Obligations and Collateralized Loan Obligations [Member] Investments at fair value [Member] Investments [Member] Long-term debt [Member] Long-term Debt [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] Investments at fair value Investments, Net Asset Value, Fair Value Disclosure Investments, Net Asset Value, Fair Value Disclosure 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 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 greater than 90 days 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 Other changes in fair value Fair Value, Option, Changes in Fair Value, Gain (Loss) Number of operating segments Number of Operating Segments Compensation and Retirement Disclosure [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] U.S Pension Plan [Member] United States Pension Plan of US Entity [Member] German Pension Plan [Member] Foreign Pension Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Components of net periodic pension cost (income): Components Of Net Pension Cost [Abstract] Components of net pension cost. Service cost Defined Benefit Plan, Service Cost Interest cost on projected benefit obligation Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Net amortization Defined Benefit Plan, Amortization of Gains (Losses) Net periodic pension income Defined Benefit Plan, Net Periodic Benefit Cost Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Equity Long/Short Hedge Funds [Member] Hedge Funds, Equity Long (Short) [Member] Fixed Income and High Yield Hedge Funds [Member] High Yield Hedge Funds [Member] High Yield Hedge Funds. Fund of Funds [Member] Fund Of Funds [Member] Fund of Funds. Equity Funds [Member] Equity Fund [Member] Equity Funds. Multi-asset Funds [Member] Multi-asset Funds [Member] Multi-asset Funds [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 Investments, Fair Value Disclosure Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Redemption Frequency (if currently eligible) Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency Sovereign obligations [Member] Sovereign Debt Securities [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Net derivatives [Member] Derivative Financial Instruments, Liabilities [Member] Loans [Member] Loans [Member] Other secured financings [Member] Other Secured Financings At Fair Value [Member] Other Secured Financings At Fair Value [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) relating to instruments still held Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Liabilities: Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliations, 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) relating to instruments still held Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Fair value of derivative instruments in a liability position Derivative, Net Liability Position, Aggregate Fair Value Collateral posted for derivative instruments in a liability position Collateral Already Posted, Aggregate Fair Value Additional collateral required for derivative instruments in a liability position Additional Collateral, Aggregate Fair Value Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Private equity funds [Member] Private Equity Funds [Member] Percentage of investment at fair value in liquidation Percentage of Investment at Fair Value in Liquidation Percentage of Investment at Fair Value in Liquidation Estimated period for the liquidation of the underlying assets, Minimum Estimated Period For Liquidation Of Underlying Assets Minimum Estimated period for the liquidation of the underlying assets, Minimum. Estimated period for the liquidation of the underlying assets, Maximum Estimated Period For Liquidation Of Underlying Assets Maximum Estimated period for the liquidation of the underlying assets, maximum. 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. Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Related party private equity vehicles [Member] Private Equity Vehicles [Member] Private equity vehicles. Other private investment vehicles [Member] Other Private Investment Vehicles [Member] Other Private Investment Vehicles [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] JCP Entities [Member] JCP Entities [Member] JCP Entities [Member] Jefferies Energy Partners I LP [Member] Jefferies Energy Partners I LP [Member] Jefferies Energy Partners I LP [Member] Agency mortgage-backed securities [Member] Mortgage And Asset Backed Securitization Activity Agency [Member] Mortgage and asset backed securitization activity agency. Non agency mortgage-backed securities [Member] Mortgage And Asset Backed Securitization Activity Non Agency [Member] Mortgage and asset backed securitization activity non agency. Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] 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. Maximum exposure Guarantee Obligations Maximum Exposure Fair Value Guarantee obligations maximum exposure fair value. Carrying amount Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets Collateralized Transactions Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block] Jefferies Finance, LLC [Member] Jefferies Finance Llc [Member] Jefferies Finance LLC. Jefferies LoanCore, LLC [Member] Jefferies Loan Core Llc [Member] Jefferies loan core LLC. JCP Fund V [Member] JCP Funds [Member] JCP Funds [Member] Summary of Selected Financial Information Equity Method Investments [Table Text Block] Total assets Equity Method Investment, Summarized Financial Information, Assets Total liabilities Equity Method Investment, Summarized Financial Information, Liabilities Total partners’ capital Equity Method Investment Summarized Financial Information, Equity 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 Security Owned and Sold, Not yet Purchased, at Fair Value [Axis] Security Owned and Sold, Not yet Purchased, at Fair Value [Axis] Security Owned and Sold, Not yet Purchased Fair Value, Security Name [Domain] Security Owned and Sold, Not yet Purchased Fair Value, Security Name [Domain] Financial Instruments Owned [Member] Financial Instruments Owned [Member] Financial Instruments Owned [Member] Financial Instruments Sold, Not Yet Purchased [Member] Financial Instruments Sold, Not Yet Purchased [Member] Financial Instruments Sold, Not Yet Purchased [Member] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Derivatives [Member] Derivative [Member] Eligible Item or Group for Fair Value Option [Axis] Fair Value, Option, Eligible Item or Group [Domain] Non-exchange traded securities [Member] Non Exchange Traded Securities [Member] Non-exchange traded securities. Private equity securities [Member] Private Equity Securities [Member] Private equity securities. Equity swaps [Member] Equity Swap [Member] Equity options [Member] Equity Option [Member] Unfunded commitment [Member] Unfunded Commitments [Member] Unfunded Commitments [Member] Variable funding note swaps [Member] Variable Funding Note Swaps [Member] Variable Funding Note Swaps [Member] Total return swaps [Member] Total Return Swap [Member] Credit default swaps [Member] Credit Default Swap [Member] Valuation Technique [Axis] Valuation Technique [Axis] Valuation Technique [Domain] Valuation Technique [Domain] Market approach [Member] Market Approach Valuation Technique [Member] Convertible bond model [Member] Convertible Bond Model [Member] Convertible Bond Model [Member] Discounted cash flows [Member] Discounted Cash Flow Approach [Member] Discounted Cash Flow Approach [Member] Comparable pricing [Member] Market Pricing [Member] Market Pricing [Member] Present value [Member] Present Value [Member] Present Value [Member] Scenario analysis [Member] Scenario Analysis [Member] Scenario Analysis [Member] Option model/default rate [Member] Option Model/Default Rate Valuation Technique [Member] Option Model/Default Rate Valuation Technique [Member] Option model [Member] Valuation Technique Option Model [Member] Valuation Technique Option Model [Member] Default rate [Member] Default Rate Valuation Technique [Member] Default Rate Valuation Technique [Member] Weighted Average [Member] Weighted Average [Member] Instruments owned, fair value Instruments sold, not yet purchased, fair value Significant Unobservable Input(s), Price Fair Value Inputs, Price Fair Value Inputs, Price Significant Unobservable Input(s), Underlying stock price (in dollars per share) Share Price Significant Unobservable Input(s), Comparable asset price Fair Value Inputs, Comparable Asset Price Fair Value Inputs, Comparable Asset Price Significant Unobservable Input(s), Volatility Fair Value Assumptions, Expected Volatility Rate Significant Unobservable Input(s), Discount rate/yield Cash Flow Discount Rate Cash Flow Discount Rate Significant Unobservable Input(s), Estimated recovery percentage Fair Value Assumptions Estimated Recovery Percentage Fair value assumptions estimated recovery percentage. Significant Unobservable Input(s), Cumulative loss rate Cumulative Loss Rate Cumulative Loss Rate Significant Unobservable Input(s), Duration Fair Value Inputs, Duration Fair Value Inputs, Duration Significant Unobservable Input(s), EBITDA (a) multiple Fair Value Inputs, Earnings before Interest, Taxes, Depreciation, and Amortization Multiple Significant Unobservable Input(s), Constant prepayment rate Fair Value Inputs, Prepayment Rate Significant Unobservable Input(s), Constant default rate / Credit spread Fair Value Inputs, Entity Credit Risk Significant Unobservable Input(s), Loss severity Fair Value Inputs, Loss Severity Significant Unobservable Input(s), Transaction level Fair Value Inputs, Transaction Level, Amount Fair Value Inputs, Transaction Level, Amount Significant Unobservable Input(s), Average silver production Fair Value Inputs, Average Silver Production Fair Value Inputs, Average Silver Production Significant Unobservable Input(s), Yield Valuation Yield Estimated yield in a DCF applied in estimating the fair value of financial assets and liabilities. Significant Unobservable Input(s), Transaction level (in dollars per share) Transaction Level Price Per Share Transaction Level Price Per Share Significant Unobservable Input(s), Default probability Fair Value Inputs, Probability of Default 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 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 Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Severance Costs [Member] Employee Severance [Member] Accelerated Amortization of Restricted Stock and Restricted Cash Awards [Member] Accelerated Amortization of Restricted Stock and Restricted Cash Awards [Member] Accelerated Amortization of Restricted Stock and Restricted Cash Awards [Member] Contract Termination Costs [Member] Contract Termination [Member] Other Expenses [Member] Other Restructuring [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Compensation and Benefits [Member] Compensation and Benefits [Member] Compensation and Benefits [Member] Technology and Communications [Member] Technology and Communications [Member] Technology and Communications [Member] Other Expense [Member] Other Expense [Member] Restructuring and impairment costs Restructuring and Related Cost, Impairment Costs Restructuring and Related Cost, Impairment Costs Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Variable Interest Entities [Member] Variable Interest Entities [Member] Variable Interest Entities [Member] Statement [Line Items] Statement [Line Items] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Pledged financial instruments Pledged Financial Instruments, Not Separately Reported, Securities Financial instruments, owned, at fair value Financial Instruments, Owned, at Fair Value Fees, interest and other Fees Interest And Other Represents accounts receivable from clients, counterparties and others, interest income receivable, dividend income receivable, fees receivable, and other receivables from suppliers, insurance companies and amounts due from third parties. Other assets Other Assets Other secured financings at fair value Other Secured Financings, Fair Value Disclosure Other Secured Financings, Fair Value Disclosure Other secured financings Other Secured Financings Accrued expenses and other liabilities Accounts Payable and Accrued Liabilities Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net earnings (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net earnings (loss) to net cash provided by (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) loss 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] Cash and securities segregated and on deposit for regulatory purposes or 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 Investments in managed funds Increase Decrease In Investments In Managed Funds The net change during the reporting period of the investments in funds managed by the firm and investments in third-party managed funds in which we are entitled to a portion of the management and/or performance fees. 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 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 Payment on purchase of aircraft Payments to Acquire Other Property, Plant, and Equipment Deconsolidation of asset management entity Deconsolidation of Asset Management Entity Deconsolidation of Asset Management Entity Cash received from contingent consideration Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset 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 Net (payments on) proceeds from other secured financings Proceeds from (Payments for) Other Financing Activities Net proceeds from issuance of long-term debt, net of issuance costs Proceeds from Issuance of Senior Long-term Debt Net change in bank overdrafts Net cash provided by financing activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents 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 Income taxes, net Income Taxes Paid, Net 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, Quantitative Disclosures [Table Text Block] Investment in insurance contract Investment In Insurance Contract Investment in insurance contract. Trading Securities [Table] Trading Securities [Table] U.S. government agency residential mortgage-backed securities [Member] Us Government Agency Issued Rmbs [Member] Us Government Agency Issued Rmbs [Member] U.S. government agency commercial mortgage-backed securities [Member] Us Government Agency Issued Cmbs [Member] Us Government Agency Issued Cmbs [Member] Collateralized loan obligations [Member] Collateralized Loan Obligations [Member] Consumer and other loans [Member] Other Debt Obligations [Member] Schedule of Trading Securities and Other Trading Assets [Line Items] Schedule of Trading Securities and Other Trading Assets [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 Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Loss Contingencies [Table] Loss Contingencies [Table] Jefferies Capital Partners LLC [Member] Jefferies Capital Partners Llc [Member] Jefferies capital partners, LLC. Other Investments [Member] 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 [Member] 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 mortgage-related commitments Mortgage Related Commitments At Fair Value Mortgage related commitments at fair value. Fair value of derivative contracts approximated deemed to meet the definition of a guarantee Maximum amount payable under guarantee Loans Payable 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 Nonvested Share-Based Awards [Member] Nonvested Share Awards [Member] Nonvested Share Awards [Member] Remaining Unamortized Amounts Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted Average Vesting Period (in Years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Securitization Vehicles [Member] Securitization Activity [Member] Securitization Activity [Member] Other [Member] Other Activity [Member] Other activity. Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Cash [Member] Cash [Member] Securities Purchased Under Agreement to Resell [Member] Securities Purchased Under Agreement [Member] Securities Purchased Under Agreement [Member] Fees, Interest and Other Receivables [Member] Fees, Interest and Other Receivables [Member] Fees, Interest and Other Receivables [Member] Other Secured Financings [Member] Other Secured Financings [Member] Other Secured Financings [Member] Other Liabilities [Member] Other Liabilities [Member] Assets Variable Interest Entity, Consolidated, Carrying Amount, Assets Liabilities Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Equity Method Investee [Member] 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 [Member] 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] 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 Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Other Assets [Member] Other Assets [Member] Accounts Payable and Accrued Liabilities [Member] Accounts Payable and Accrued Liabilities [Member] Guarantee Obligations [Line Items] Guarantor Obligations [Line Items] Equity commitment Equity Commitment, Amount Equity Commitment, Amount Total committed equity capitalization of JIFN 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. Unfunded commitment fees income Line of Credit Facility, Unfunded Commitment Fee Income Line of Credit Facility, Unfunded Commitment Fee Income Interest income Investments in and Advances to Affiliates, Dividend or Interest Credited to Income Net underwriting fees paid by JFIN related to originations of loans by JFIN Fees Earned To Joint Venture Related To Loan Origination Fees paid to joint venture related to loan origination. Fees paid to JFIN related to origination of loans by JFIN Fees Paid To Joint Venture Related To Loan Origination Fees paid to joint venture related to loan origination. Commissions for conducting brokerage services Brokerage Commissions Revenue Investment banking revenue Investment Banking Revenue Administrative services provided Administrative Services Revenue Receivables under service agreement Due from Related Parties Payables under service agreement Due to Related Parties Financial instruments sold, not yet purchased, at fair value Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Member's paid-in capital [Member] Members Paid In Capital [Member] Members Paid In Capital [Member] Accumulated other comprehensive income (loss) [Member] AOCI Attributable to Parent [Member] Noncontrolling interests [Member] Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Total member’s equity Members' Equity [Abstract] Beginning Balance Stockholders' Equity Attributable to Parent Net earnings attributable to Jefferies Group LLC Net Income Attributable To Parent Net Income Loss Available To Common Stockholders Basic Net Income Attributable To Parent Net Income Loss Available To Common Stockholders Basic Tax detriment for issuance of share-based awards Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Currency adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Changes in instrument specific credit risk, net of tax 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 Pension adjustments, net of tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Ending Balance Noncontrolling interests: Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] Beginning Balance Stockholders' Equity Attributable to Noncontrolling Interest Net earnings (loss) attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Contributions Noncontrolling Interest, Increase from Subsidiary Equity Issuance Distributions Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Deconsolidation of asset management company Consolidation Deconsolidation Of Asset Management Entity Consolidation Deconsolidation Of Asset Management Entity Ending Balance Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest 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. Revenues: Revenues [Abstract] Commissions and other fees Principal transactions Principal Transactions Revenue, Net Investment banking Asset management fees and investment income from managed funds 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 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 Other Other Expenses Total non-compensation expenses Non Compensation Expenses Non Compensation Expenses Total non-interest expenses Earnings (loss) before income taxes Income tax expense (benefit) Income Tax Expense (Benefit) Net earnings (loss) Net earnings attributable to noncontrolling interests Net earnings (loss) attributable to Jefferies Group LLC Net Income (Loss) Attributable to Parent Revenue Recognition Policies Revenue Recognition, Policy [Policy Text Block] Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Securities Segregated and on Deposit for Regulatory Purposes or Deposited With Clearing and Depository Organizations Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Financial Instruments and Fair Value Fair Value of Financial Instruments, Policy [Policy Text Block] Investments in Managed Funds Investments In Managed Funds Policy [Policy Text Block] Disclosure of accounting policy for investments in managed funds. Loans to and Investments in Related Parties Loans Receivable And Investments In Related Parties Policy [Policy Text Block] Disclosure of accounting policy for loans to and investments in related parties. Securities Borrowed and Securities Loaned Securities Borrowed and Loaned Policy [Policy Text Block] Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase Repurchase and Resale Agreements Policy [Policy Text Block] Offsetting of Derivative Financial Instruments and Securities Financing Agreements Derivatives, Offsetting Fair Value Amounts, Policy [Policy Text Block] Hedge Accounting Derivatives, Methods of Accounting, Hedging Derivatives [Policy Text Block] Premises and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Goodwill and Intangible Assets Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Legal Reserves Liability Reserve Estimate, Policy [Policy Text Block] Share-based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Securitization Activities Transfers and Servicing of Financial Assets, Policy [Policy Text Block] Accounting Standards to be Adopted in Future Periods and Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Compensation Plans Compensation Related Costs, General [Text Block] Summary of Interest Income, Other Revenues and Investment Income Attributable to Related Party Private Equity Funds Interest and Other Income [Table Text Block] Exit Costs Restructuring and Related Activities Disclosure [Text Block] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Americas [Member] Americas [Member] Europe [Member] Europe [Member] Asia [Member] Asia [Member] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Derivative [Table] Derivative [Table] Equity Swaps And Options [Member] Equity Swaps And Options [Member] Equity Swaps And Options [Member] Credit Default Swap [Member] Total Return Swap [Member] Foreign Currency Forwards Swaps And Options [Member] Foreign Currency Forwards Swaps And Options [Member] Foreign currency forwards swaps and options. Fixed Income Forwards [Member] Fixed Income Forward Contracts [Member] Fixed Income Forward Contracts [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. 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. 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. Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Interest rate swaps [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 Investment Equity Method Investments Losses from investment Income (Loss) from Equity Method Investments 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 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] Summary of Long-Term Debt Carrying Values Including Unamortized Discounts and Premiums Schedule of Long-term Debt Instruments [Table Text Block] Commitments and Contingencies Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block] Guarantees Schedule of Guarantor Obligations [Table Text Block] External Credit Ratings of Underlying or Referenced Assets for Credit Related Derivatives Contracts Commitments And Guarantee Obligations External Credit Rating Table [Table Text Block] Commitments and guarantee obligations external credit rating. Schedule of Gain (Loss) on Investments [Table] Schedule of Gain (Loss) on Investments [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] Gain (Loss) on Investments [Line Items] Gain (Loss) on Investments [Line Items] Loans and other receivables Fair Value, Option, Credit Risk, Gains (Losses) on Assets Financial Instruments Sold and Long-term Debt Gains (losses) due to changes in instrument specific credit risk Fair Value, Option, Credit Risk, Gains (Losses) on Liabilities Commitments, Contingencies and Guarantees Commitments Contingencies and Guarantees [Text Block] Income Taxes Income Tax Disclosure [Text Block] Restructuring and Related Costs Restructuring and Related Costs [Table Text Block] Investments Investment [Text Block] Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Long-Term Debt Long-term Debt [Text Block] 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] Loans and other receivables Fair Value, Option, Aggregate Differences, Loans and Long-term Receivables Loans and other receivables on nonaccrual status and/or greater than 90 days past due Fair Value, Option, Loans Held as Assets, Aggregate Amount in Nonaccrual Status, Aggregated Difference Loans and other receivables greater than 90 days past due Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due, Aggregate Difference Long-term debt Fair Value, Option, Aggregate Differences, Long-term Debt Instruments Total equity Equity Method Investment, Summarized Financial Information, Equity Excluding Noncontrolling Interests Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Number of years in which restricted stock awards amortized as compensation expense Period In Which Restricted Stock Awards Amortized As Compensation Expense