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] Non-vested share-based awards Nonvested Share Awards [Member] Nonvested Share Awards [Member] Restricted cash awards Restricted Cash Awards [Member] Restricted Cash Awards [Member] Compensation Plans [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] 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 Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Income Statement [Abstract] Revenues: Revenues [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 Revenues Interest expense Interest Expense Net revenues Revenues, Net of Interest Expense 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 Noninterest Expense Earnings before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Net earnings Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net earnings (loss) attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net earnings attributable to Jefferies Group LLC Net Income (Loss) Attributable to Parent Debt Disclosure [Abstract] Short-Term Borrowings Short-term Debt [Text Block] Revenue from Contract with Customer [Abstract] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Accounting Policies [Abstract] Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Statement of Cash Flows [Abstract] Cash, Cash Equivalents and Restricted Cash by Category [Abstract] Cash and Cash Equivalents [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Cash and securities segregated and on deposit for regulatory purposes with clearing and depository organizations Cash And Securities Segregated And On Deposit For Regulatory Purposes With Clearing And Depository Organizations Cash And Securities Segregated And On Deposit For Regulatory Purposes With Clearing And Depository Organizations Total cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Director Director [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Affiliated Entity Affiliated Entity [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Loans outstanding to certain employees Loans and Leases Receivable, Related Parties Investment in related party Related Party Transaction, Investment Amount Related Party Transaction, Investment Amount Compensation Plans Compensation Related Costs, General [Text Block] Segment Reporting [Abstract] 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] Derivative Instruments and Hedging Activities Disclosure [Abstract] 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 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] Net revenues Number of operating segments Number of Operating Segments Fair Value Disclosures [Abstract] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Loans and other receivables Loans and Finance Receivables [Member] Investments at fair value Investments [Member] CDOs and CLOs Collateralized Debt Obligations and Collateralized Loan Obligations [Member] Collateralized Debt Obligations and Collateralized Loan Obligations [Member] Net derivatives Derivative Financial Instruments, Liabilities [Member] Structured Notes Structured Notes [Member] Structured Notes [Member] CMBS Commercial Mortgage Backed Securities [Member] Other ABS Other Asset Backed Securities [Member] Other asset-backed securities. RMBS Residential Mortgage Backed Securities [Member] Long-term debt Long-term Debt [Member] US Treasury Securities US Treasury Securities [Member] 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 1 Fair Value, Inputs, Level 1 [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] 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 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 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. Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Level 2 and Level 3 Fair Value, Inputs, Level 2 And Level 3 [Member] Fair Value, Inputs, Level 2 And Level 3 [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest rate swaps Interest Rate Swap [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] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 8.500% Senior Notes Eight Point Five Percentage Senior Notes Due Two Thousand Nineteen [Member] 8.5% Senior Notes, due 2019. 2.375% Euro Medium Term Notes 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 Notes Six Point Eight Seven Five Percentage Senior Notes Due Two Thousand Twenty One [Member] 6.875% Senior Note, due 2021. 2.250% Euro Medium Term Notes 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 Five Point One Two Five Percentage Senior Notes Due Two Thousand Twenty Three [Member] 5.125 % Senior Notes due 2023. 4.850% Senior Notes Four Point Eight Five Percentage Senior Notes, Due 2027 [Member] Four Point Eight Five Percentage Senior Notes, Due 2027 [Member] 6.450% Senior Debentures Six Point Four Five Percentage Senior Debentures Due Two Thousand Twenty Seven [Member] 6.45% Senior Debentures due 2027. 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] 6.250% Senior Debentures Six Point Two Five Percentage Senior Debentures Due Two Thousand Thirty Six [Member] 6.25% Senior Debentures, due 2036. 6.500% Senior Notes Six Point Five Zero Percentage Senior Notes Due Two Thousand Forty Three [Member] 6.50% Senior Notes due 2043. Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt instrument interest rate Debt Instrument, Interest Rate, Stated Percentage Effective Interest Rate Debt Instrument, Interest Rate, Effective Percentage Long-term debt Long-term Debt Debt principal amount Debt Instrument, Face Amount (Loss) gain associated with an interest rate swap based on its designation as a fair value hedge Gain (Loss) on Fair Value Hedges Recognized in Earnings Long-term debt at fair value Long-term Debt, Fair Value Corporate debt securities Corporate Debt Securities [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Jefferies Jefferies Financial Group Inc. [Member] Jefferies Financial Group Inc. [Member] Hedge Fund Managed By Jefferies Hedge Fund Managed By Jefferies Financial Group Inc. [Member] Hedge Fund Managed By Jefferies Financial Group Inc. [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Investment banking Investment Banking [Member] Investment Banking [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] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Accrued expenses and other liabilities Accounts Payable and Accrued Liabilities [Member] Payables - brokers, dealers and clearing organizations Payables, Brokers, Dealers And Clearing Organizations [Member] Payables, Brokers, Dealers And Clearing Organizations [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 Payments of distributions to affiliates Payments of Distributions to Affiliates Distribution to affiliates, approved amount Due to Affiliate Distribution payable accrued during period Increase (Decrease) in Due to Affiliates 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 Proceeds from sale of securities Proceeds from Sale of Debt Securities, Available-for-sale Payments to acquire securities 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 Payables to Broker-Dealers and Clearing Organizations Financial instruments owned, at fair value Financial Instruments, Owned, at Fair Value Financial instruments sold, not yet purchased, at fair value Financial Instruments Sold, Not yet Purchased, at Fair Value Banking and Thrift [Abstract] 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 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] 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 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. Short-term borrowings Short-term Debt [Member] Gain (Loss) on Securities [Line Items] Gain (Loss) on Securities [Line Items] Financial instruments owned: Financial Instruments, Owned, at Fair Value [Abstract] 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) 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] CLOs Collateralized Loan Obligations [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 Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] 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 Equity Commitments Committed equity capitalization. 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 Long-Term Debt Long-term Debt [Text Block] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net earnings Adjustments to reconcile net earnings 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 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, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Net 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 and restricted cash at end of period Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid 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 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 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 Statement of Comprehensive Income [Abstract] Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Currency translation and other adjustments 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 Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to Jefferies Group LLC Comprehensive Income (Loss), Net of Tax, Attributable to Parent Equity Method Investments and Joint Ventures [Abstract] 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] 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] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] 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 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] 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] 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 Schedule of Goodwill [Table] Schedule of Goodwill [Table] 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] 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 Derivative [Table] Derivative [Table] 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. 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. 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. Berkadia Commercial Mortgage, LLC Berkadia Commercial Mortgage, LLC [Member] Berkadia Commercial Mortgage, LLC [Member] Ownership percentage Equity Method Investment, Ownership Percentage 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 Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents ($1,129 and $1,096 at May 31, 2019 and November 30, 2018, respectively, related to consolidated VIEs) Financial instruments owned, at fair value (including securities pledged of $12,176,602 and $13,059,802 at May 31, 2019 and November 30, 2018, respectively; and $353 and $380 at May 31, 2019 and November 30, 2018, respectively, related to consolidated VIEs) Loans to and investments in related parties Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Securities borrowed Securities Borrowed Securities purchased under agreements to resell (includes $25,000 and $0 at fair value at May 31, 2019 and November 30, 2018, respectively) Securities Purchased under Agreements to Resell Receivables: Receivables [Abstract] Brokers, dealers and clearing organizations Receivables from Brokers-Dealers and Clearing Organizations Customers Receivables from Customers 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. Premises and equipment Property, Plant and Equipment, Net Goodwill Other assets ($2 at both May 31, 2019 and November 30, 2018, related to consolidated VIEs) Other Assets Total assets Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Short-term borrowings Short-term Debt Collateralized financings: Collateralized Financings [Abstract] Securities loaned Securities Loaned Securities sold under agreements to repurchase Securities Sold under Agreements to Repurchase Other secured financings (includes $1,265,800 and $881,472 at May 31, 2019 and November 30, 2018, respectively, related to consolidated VIEs) Other Secured Financings Payables: Payables [Abstract] Payables. Brokers, dealers and clearing organizations Customers Payables to Customers Accrued expenses and other liabilities ($1,148 and $642 at May 31, 2019 and November 30, 2018, respectively, related to consolidated VIEs) Accounts Payable and Accrued Liabilities Long-term debt (includes $819,509 and $686,170 at fair value at May 31, 2019 and November 30, 2018, respectively) Total liabilities Liabilities EQUITY Equity [Abstract] Member’s paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive income (loss): Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Currency translation adjustments Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Changes in instrument specific credit risk Accumulated Other Comprehensive Income (Loss), Changes in Instrument Specific Credit Risk, Net of Tax Accumulated Other Comprehensive Income (Loss), Changes in Instrument Specific Credit Risk, Net of Tax Cash flow hedges Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Additional minimum pension liability Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Available-for-sale securities Accumulated Other Comprehensive Income (Loss), Debt Securities, Available-for-sale, Adjustment, after Tax Total accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total Jefferies Group LLC member’s equity Members Common Stockholders Equity Members Common Stockholders Equity Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Equity And Members Equity Stockholders Equity Including Portion Attributable To Noncontrolling Interest Equity And Members Equity Stockholders Equity Including Portion Attributable To Noncontrolling Interest Total liabilities and equity Liabilities Equity And Members Equity Stockholders Equity Liabilities Equity And Members Equity Stockholders Equity Collateralized Transactions Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [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. Summary of Selected Financial Information Equity Method Investments [Table Text Block] Securities purchased under agreements to resell Securities Purchased Under Agreements To Resell [Member] Securities Purchased Under Agreements To Resell [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 Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Percentage of profits received from joint venture Percentage Of Profits Received From Joint Venture Percentage Of Profits Received From Joint Venture Purchase commitment amount Purchase Commitment Amount Purchase Commitment Amount Distribution received from equity method investment Proceeds from Equity Method Investment, Distribution 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 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 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 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 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 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 Revenues from Contracts with Customers Revenue from Contract with Customer [Text Block] 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. 5.125% Senior Notes Five Point One Two Five Percentage Senior Notes Due Two Thousand Eighteen [Member] 5.125% Senior Notes, due 2018. Increase (decrease) of long-term debt Increase (Decrease) of Long-term Debt Increase (Decrease) of Long-term Debt Repayments of debt Repayments of Debt Redemption price as percentage of principal amount redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Brokers and Dealers [Abstract] Net Capital, Adjusted and Excess Net Capital Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [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] Schedule of related party transactions Schedule of Related Party Transactions [Table Text Block] Epic Gas Epic Gas [Member] Epic Gas [Member] 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 Investment in Epic Gas Equity Method Investments Net earnings (losses) Equity Method Investment, Summarized Financial Information, Net Income (Loss) Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Non-interest expenses Earnings before income taxes Segment assets 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] Income Tax Disclosure [Abstract] 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) Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Variable Interest Entities Variable Interest Entities [Member] Variable Interest Entities [Member] Statement [Line Items] Statement [Line Items] Pledged financial instruments Pledged Financial Instruments, Not Separately Reported, Securities Securities purchased under agreements to resell, fair value Securities Purchased Under Agreements To Resell, Fair Value Securities Purchased Under Agreements To Resell, Fair Value Other assets Other secured financings Accrued expenses and other liabilities 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] 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 Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Income Taxes Income Tax Disclosure [Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Commissions and other fees Commissions And Other Fees [Member] Commissions And Other Fees [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] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenues from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Revenues 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] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] 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. 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. Adjustment related to foreign currency gains reclassified to earnings Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax 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 Cash flow hedge losses reclassification amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after 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 Summary of Long-Term Debt Carrying Values Including Unamortized Discounts and Premiums Schedule of Long-term Debt Instruments [Table Text Block] JCP Fund V JCP Funds [Member] JCP Funds [Member] Total committed equity capitalization Commitments Under Equity Capitalization Of Joint Venture Entity Commitments under equity capitalization of joint venture entity. Unfunded portion of equity commitment to subsidiary Equity Commitment To Joint Venture Unfunded Portion Equity commitment to joint venture unfunded portion. Percent of financial information presented Equity Method Investment, Percent of Financial Information Presented Equity Method Investment, Percent of Financial Information Presented 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. 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 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 Notes Payable to Banks [Member] Floating rate puttable notes Puttable Notes [Member] Puttable Notes [Member] Intraday Credit Facility Intraday Credit Facility [Member] Intraday Credit Facility [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Federal funds effective rate Federal Funds Effective Swap Rate [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Short-term borrowings Interest rate on short-term borrowings outstanding Short-term Debt, Weighted Average Interest Rate, at Point in Time 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 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 Investments Investment [Text Block] 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] Fair Value Disclosures Fair Value Disclosures [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [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] Municipal securities Sovereign obligations Sovereign Debt Securities [Member] Residential mortgage-backed securities Commercial mortgage-backed securities Other asset-backed securities Loans and other receivables Investments at fair value Investments At Fair Value [Member] Investments At Fair Value [Member] 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 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 Derivative assets Derivative Asset Counterparty and Cash Collateral Netting Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset Securities purchased under agreements to resell Liabilities: Fair Value Liabilities Measured On Recurring Basis [Abstract] Fair value liabilities measured on recurring basis. Financial instruments sold, not yet purchased: Derivative liabilities Derivative Liability Counterparty and Cash Collateral Netting Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Long-term debt Commitments and Contingencies Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block] Guarantees Schedule of Guarantor Obligations [Table Text Block] Related party private equity vehicles Private Equity Vehicles [Member] Private equity vehicles. Other investment vehicles Other Investment Vehicles [Member] Other Investment Vehicles [Member] 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 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 Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets 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] Segment Reporting Segment Reporting Disclosure [Text Block] Consolidation Consolidation, Policy [Policy Text Block] Accounting Standards to be Adopted in Future Periods New Accounting Pronouncements, Policy [Policy Text Block] Revenues from Contracts with Customers Revenue from Contract with Customer [Policy Text Block] Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Jefferies Finance, LLC Jefferies Finance Llc [Member] Jefferies Finance LLC. 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 Our total equity balance Net earnings 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 Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] 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] Guarantee Obligations [Line Items] Guarantor Obligations [Line Items] 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 Equity Method Investee Equity Method Investee [Member] 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] 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 Commitments, Contingencies and Guarantees Commitments Contingencies and Guarantees [Text Block] Promissory Note Promissory Note [Member] Promissory Note [Member] 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] Equity commitment Equity Commitment, Amount Equity Commitment, Amount Total committed equity capitalization of JFIN Funded portion of equity commitment to subsidiary Equity Commitment To Joint Venture Funded Portion Equity commitment to joint venture funded 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 Document And Entity Information [Abstract] Document and Entity Information Abstract. Document Type Document Type Document Period End Date Document Period End Date Entity Registrant Name Entity Registrant Name Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year 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 Securitization Activities Transfers and Servicing of Financial Assets [Text Block] Non-exchange-traded securities Non Exchange Traded Securities [Member] Non-exchange traded securities. Derivatives Private equity securities Private Equity Securities [Member] Private equity securities. Equity options Equity Option [Member] Total return swaps 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] Underlying stock price Measurement Input, Share Price [Member] Comparable price Measurement Input, Comparable Asset Price [Member] Measurement Input, Comparable Asset Price [Member] Basis points upfront Measurement Input, Basis Points [Member] Measurement Input, Basis Points [Member] Transaction level Measurement Input, Transaction Level [Member] Measurement Input, Transaction Level [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] Spread to 6 month LIBOR Measurement Input, Spread To 6 Month LIBOR [Member] Measurement Input, Spread To 6 Month LIBOR [Member] Volatility Measurement Input, Price Volatility [Member]