Compensation Related Costs [Abstract] 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 Period In Which Restricted Stock Awards Amortized As Compensation Expense Minimum work hours required for part-time employees to purchase ESPP Share Based Compensation Arrangement By Employee Stock Purchase Plan, Minimum Work Hours Required for Part-time Employees Share Based Compensation Arrangement By Employee Stock Purchase Plan, Minimum Work Hours Required for Part-time Employees Annual employee contributions Share Based Compensation Arrangement By Employee Stock Purchase Plan Maximum Employee Contribution Share based compensation arrangement by maximum employee contributions to employee stock purchase plan. Employee service share based compensation plan stock price Share Based Compensation Arrangement By Employee Stock Purchase Plan Exercise Price Of Share Percentage of closing stock price used to purchase shares under the employee stock purchase plan. Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] 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] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Corporate equity securities Equity Securities [Member] Corporate debt securities Corporate Debt Securities [Member] CDOs and CLOs Collateralized Debt Obligations and Collateralized Loan Obligations [Member] Collateralized Debt Obligations and Collateralized Loan Obligations [Member] U.S. government and federal agency securities US Treasury and Government [Member] Municipal securities Municipal Bonds [Member] Sovereign obligations Sovereign Debt Securities [Member] Residential mortgage-backed securities Residential Mortgage Backed Securities [Member] Commercial mortgage-backed securities Commercial Mortgage Backed Securities [Member] Other asset-backed securities Other Asset Backed Securities [Member] Other asset-backed securities. Loans and other receivables Loans and Finance Receivables [Member] Investments at fair value Investments At Fair Value [Member] Investments At Fair Value [Member] Loans Loans [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: Financial Instruments, Owned, at Fair Value [Abstract] 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 received as collateral Securities Received as Collateral 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] Financial instruments sold, not yet purchased, at fair value Financial Instruments Sold, Not yet Purchased, at Fair Value Derivative liabilities Derivative Liability Counterparty and Cash Collateral Netting Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Short-term borrowings Short-term Debt, Fair Value Long-term debt Long-term Debt, Fair Value Obligation to return securities received as collateral Obligation to Return Securities Received as Collateral Accounting Changes and Error Corrections [Abstract] Schedule of New Accounting Pronouncements Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Revenue from Contract with Customer [Abstract] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Commissions and other fees Commissions And Other Fees [Member] Commissions And Other Fees [Member] Investment banking Investment Banking [Member] Investment Banking [Member] Asset management fees Asset Management Fees [Member] Asset Management Fees [Member] Other Revenue From Contract With Customers, Other [Member] Revenue From Contract With Customers, Other [Member] Principal transactions Principal Transactions Revenue [Member] Principal Transactions Revenue [Member] Interest Interest Revenue [Member] Interest Revenue [Member] Other Other Sources Of Revenue, Miscellaneous [Member] Other Sources Of Revenue, Miscellaneous [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenues from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Revenues Revenues Banking and Thrift [Abstract] 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] Equity Method Investments and Joint Ventures [Abstract] Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Collateralized Transactions Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] RMBS CMBS Other ABS Loans and other receivables Investments at fair value Investments [Member] Net derivatives Derivative Financial Instruments, Liabilities [Member] Other secured financings Other Secured Financings At Fair Value [Member] Other Secured Financings At Fair Value [Member] Long-term debt 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] 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) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings 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) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings 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 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] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] 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] Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Jefferies Finance, LLC Jefferies Finance Llc [Member] Jefferies Finance LLC. Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Assets Other Assets [Member] Accrued expense and other liabilities Accrued Expense And Other Liabilities [Member] Accrued Expense And Other Liabilities [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Guarantee Obligations [Line Items] Guarantor Obligations [Line Items] Equity commitment Equity Commitment, Amount Equity Commitment, Amount Total committed equity capitalization of JFIN Commitments Under Equity Capitalization Of Joint Venture Entity Commitments under equity capitalization of joint venture entity. Funded portion of equity commitment to subsidiary Equity Commitment To Joint Venture Funded Portion Equity commitment to joint venture funded portion. Unfunded portion of equity commitment to subsidiary Equity Commitment To Joint Venture Unfunded Portion Equity commitment to joint venture unfunded portion. Extension period Line Of Credit Extension Period Line of credit extension period. Termination notice period Line Of Credit Termination Notice Period Line of credit termination notice period. Committed line of credit facility amount Line Of Credit Facility Commitment Under Joint Venture Line of credit facility commitment under joint venture. Funded portion of loan commitment Loan Commitment To Joint Venture Funded Portion Loan Commitment To Joint Venture Funded Portion Loan commitment Aggregate Loan Commitment Aggregate loan commitment to joint venture. Receivables under service agreement Due from Related Parties Payables under service agreement Due to Related Parties 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 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 Notes Payable to Banks [Member] Line of credit Line of Credit [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Floating rate puttable notes Puttable Notes [Member] Puttable Notes [Member] Floating rate puttable notes matured April 8, 2018 Floating Rate Puttable Notes Matured April 8, 2018 [Member] Floating Rate Puttable Notes Matured April 8, 2018 [Member] Floating rate puttable notes matured May 3, 2018 Floating Rate Puttable Notes Matured May 3, 2018 [Member] Floating Rate Puttable Notes Matured May 3, 2018 [Member] Equity-linked notes Equity-linked Notes [Member] Equity-linked Notes [Member] Equity-inked Notes Matured On December 7, 2017 Equity-Linked Notes Matured On December 7, 2017 [Member] Equity-Linked Notes Matured On December 7, 2017 [Member] Equity-linked Notes Matured On July 12, 2018 Equity-linked Notes Due July 12, 2018 [Member] Equity-linked Notes Due July 12, 2018 [Member] Equity-lined Notes Matured On July 18, 2017 Equity-lined Notes Matured On July 18, 2017 [Member] Equity-lined Notes Matured On July 18, 2017 [Member] Equity-linked Notes Matured On September 20, 2017 Equity-linked Notes Matured On September 20, 2017 [Member] Equity-linked Notes Matured On September 20, 2017 [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 Short-term Debt 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 Debt principal amount Debt Instrument, Face 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 Derivative Instruments and Hedging Activities Disclosure [Abstract] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest rate contracts Interest Rate Contract [Member] Foreign exchange contracts Foreign Exchange Contract [Member] Equity contracts Equity Contract [Member] Commodity contracts Commodity Contract [Member] Credit contracts Credit Risk Contract [Member] Exchange-traded Exchange Traded Options [Member] Cleared OTC Otc Cleared [Member] OTC Cleared [Member] Bilateral OTC Bilateral Otc [Member] Bilateral OTC [Member] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Domain] Adjustments for Change in Accounting Principle [Domain] Rule change by London Clearing House Rule Change By London Clearing House [Member] Rule Change By London Clearing House [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Fair Value, Assets Derivative Asset, Fair Value, Gross Asset Number of Contracts, Assets Derivative Asset, Number of Instruments Held Fair Value, Liabilities Derivative Liability, Fair Value, Gross Liability Number of Contracts, Liabilities Derivative Liability, Number of Instruments Held Amounts offset in the Consolidated Statements of Financial Condition, Assets Derivative Asset, Fair Value, Amount Offset Against Collateral Amounts offset in the Consolidated Statements of Financial Condition, Liabilities Derivative Liability, Fair Value, Amount Offset Against Collateral Net amounts per Consolidated Statements of Financial Condition, Assets Financial Instruments, Owned, Derivatives and Other Contractual Agreements, at Fair Value Net amounts per Consolidated Statements of Financial Condition, Liabilities Financial Instruments Sold, Not yet Purchased, Derivatives and Other Contracts Long-Term Debt Long-term Debt [Text Block] 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 Restricted Cash Awards [Member] Restricted Cash Awards [Member] Restricted stock and RSUs 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 Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] JCP Fund V JCP Funds [Member] JCP Funds [Member] Epic Gas Epic Gas [Member] Epic Gas [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Summary of Selected Financial Information Equity Method Investments [Table Text Block] Non-vested share-based awards 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 Segment Reporting [Abstract] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] 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] 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 Non-interest expenses Noninterest Expense Earnings before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Segment assets Assets 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 Net gains/(losses) on Level 3 assets (realized and unrealized) Net gains/(losses) on Level 3 liabilities (realized and unrealized) 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 Other changes in fair value Fair Value, Option, Changes in Fair Value, Gain (Loss) Cash and securities segregated and on deposit for regulatory purposes with clearing and depository organizations Cash and Securities Segregated under Federal and Other Regulations Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] HRG Group Inc. HRG Group Inc. [Member] HRG Group Inc. [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] Investment banking revenue from related parties Revenue from Related Parties Revenues from Contracts with Customers Revenue from Contract with Customer [Text Block] Number of operating segments Number of Operating Segments Jefferies Capital Partners V L.P. Jefferies Capital Partners V L.P [Member] Jefferies Capital Partners V L.P [Member] SBI USA Fund L.P. SBI USA Fund L.P. [Member] SBI USA Fund L.P. [Member] Ownership percentage Equity Method Investment, Ownership Percentage Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Director Director [Member] 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 Our investment in Epic Gas Equity Method Investments Net losses Equity Method Investment, Summarized Financial Information, Net Income (Loss) Transfers and Servicing [Abstract] Securitization Activities Transfers and Servicing of Financial Assets [Text Block] 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. Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Goodwill, Beginning Balance Goodwill Translation adjustments Goodwill, Foreign Currency Translation Gain (Loss) Goodwill, Ending Balance Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net earnings Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net earnings 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 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 provided by (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 Cash received from contingent consideration Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset Consolidation of asset management entity Consolidation Deconsolidation Of Asset Management Entity Consolidation Deconsolidation Of Asset Management Entity Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from short-term borrowings Proceeds from Short-term Debt Payments on short-term borrowings Repayments of Short-term Debt Proceeds from issuance of long-term debt, net of issuance costs Proceeds from Issuance of Senior Long-term Debt Repayment of long-term debt Repayments of Long-term Debt Dividend distribution Payments of Dividends Net proceeds from (payments on) other secured financings Proceeds from (Payments for) Other Financing Activities Net change in bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Proceeds from noncontrolling interests Proceeds from Noncontrolling Interests Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash and Cash Equivalents Net increase in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid 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 Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Berkadia Commercial Mortgage, LLC Berkadia Commercial Mortgage, LLC [Member] Berkadia Commercial Mortgage, LLC [Member] Jefferies Jefferies Financial Group Inc. [Member] Jefferies Financial Group Inc. [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] 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 Additional contribution to Investment in membership interest Additional Contribution To Investment Additional Contribution To Investment 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 Summary of Long-Term Debt Carrying Values Including Unamortized Discounts and Premiums Schedule of Long-term Debt Instruments [Table Text Block] 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 Brokerage Commissions Revenue Derivative losses Derivative, Gain (Loss) on Derivative, Net Underwriting fees Underwriting Fees Underwriting Fees Service fees Service Fees Earned Service Fees Earned KCG KCG Holdings, Inc [Member] KCG Holdings, Inc [Member] Net gain on change in fair value of investment Unrealized Gain (Loss) on Securities 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. Schedule of Short-term Borrowings Schedule of Short-term Debt [Table Text Block] 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 Non-exchange-traded securities Non Exchange Traded Securities [Member] Non-exchange traded securities. Derivatives Derivative [Member] Private equity securities Private Equity Securities [Member] Private equity securities. Total return swaps Equity options Equity Option [Member] Unfunded commitments Unfunded Commitments [Member] Unfunded Commitments [Member] Variable funding note swaps Variable Funding Note Swaps [Member] Variable Funding Note Swaps [Member] Interest rate swaps Interest Rate Swap [Member] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Market approach Valuation, Market Approach [Member] Comparable pricing Comparable Pricing Valuation Technique [Member] Comparable Pricing Valuation Technique [Member] Convertible bond model Convertible Bond Model [Member] Convertible Bond Model [Member] Discounted cash flows Discounted Cash Flow Approach [Member] Discounted Cash Flow Approach [Member] Scenario analysis Scenario Analysis [Member] Scenario Analysis [Member] Option model/default rate Option Model/Default Rate Valuation Technique [Member] Option Model/Default Rate Valuation Technique [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 asset price Measurement Input, Comparable Asset Price [Member] Measurement Input, Comparable Asset Price [Member] Discount rate/yield Measurement Input, Discount Rate [Member] Volatility Measurement Input, Price Volatility [Member] Estimated recovery percentage Measurement Input, Estimated Recovery Percentage [Member] Measurement Input, Estimated Recovery Percentage [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] Transaction level Measurement Input, Transaction Level [Member] Measurement Input, Transaction Level [Member] Default probability Measurement Input, Default Probability [Member] Measurement Input, Default Probability [Member] Credit spread Measurement Input, Credit Spread [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Weighted Average Weighted Average [Member] Financial instruments owned, measurement input Financial Instruments, Owned, Measurement Input Financial Instruments, Owned, Measurement Input Financial instruments owned, measurement input, term Financial Instruments, Owned, Measurement Input, Term Financial Instruments, Owned, Measurement Input, Term Financial instruments sold, not yet purchased, measurement input Financial Instruments Sold, Not Yet Purchased, Measurement Input Financial Instruments Sold, Not Yet Purchased, Measurement Input Derivative asset, measurement input Derivative Asset, Measurement Input Derivative liability, measurement input Derivative Liability, Measurement Input Value of asset excluded from significant unobservable inputs Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Asset Exclusion Value Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Asset Exclusion Value Value of liability excluded from significant unobservable inputs Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Exclusion Value Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Exclusion Value Short-Term Borrowings Short-term Debt [Text Block] 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 Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Jefferies LoanCore, LLC Jefferies Loan Core Llc [Member] Jefferies loan core LLC. Proceeds from sale of Jefferies LoanCore Proceeds from Sale of Equity Method Investments Period entitled to additional cash consideration Equity Method Investment Sale, Period Entitled To Additional Cash Consideration Equity Method Investment Sale, Period Entitled To Additional Cash Consideration Brokers and Dealers [Abstract] Net Capital, Adjusted and Excess Net Capital Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Purchase commitment amount Purchase Commitment Amount Purchase Commitment Amount Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Table] Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Table] Cash Cash [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] 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 Obligation To Return Securities Received As Collateral Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Amount Offset Against Collateral Total Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block] Guarantees Schedule of Guarantor Obligations [Table Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Nonconsolidated VIEs Variable Interest Entity, Not Primary Beneficiary [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] 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. 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] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Americas Americas [Member] Europe Europe [Member] Asia Asia [Member] 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. 2018 Guarantees Expected To Be Due Current Guarantees with a remaining term that matures during the fiscal year. These may include derivative guarantees, etc. 2019 Guarantees Expected To Be Due In Two Years Guarantees expected to be due within 2 fiscal years. These may include, derivative guarantees, etc. 2020 and 2021 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. 2022 and 2023 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. 2024 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 Related Party Transactions Related Party Transactions Disclosure [Text Block] Net Revenues, Expenses and Total Assets by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Net Revenues by Geographic Region Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block] Related party private equity vehicles Private Equity Vehicles [Member] Private equity vehicles. Other private investment vehicles Other Private Investment Vehicles [Member] Other Private 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 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 New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] ASC 606 Impact Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Adjusted Calculated under Revenue Guidance in Effect before Topic 606 [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 Accounting Standards Update 2014-09 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Investment banking Investment Banking Revenue Total revenues Underwriting costs Underwriting Costs Underwriting Costs Technology and communications Communications and Information Technology 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 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 Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] 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] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Accumulated other comprehensive income (loss) AOCI Attributable to Parent [Member] 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] Statement [Line Items] Statement [Line Items] 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 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. 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 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. Currency translation and other adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Aggregate amortization expense Amortization of Intangible Assets Remainder of fiscal 2018 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Year ending November 30, 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Two Year ending November 30, 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Three Year ending November 30, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Four Year ending November 30, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Five Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Subsidiary Of Jefferies Subsidiary Of Jefferies Financial Group Inc. [Member] Subsidiary Of Jefferies Financial Group Inc. [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Affiliate of Jefferies Affiliate Of Jefferies Financial Group Inc. [Member] Affiliate Of 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] Landcadia Holdings Inc. Landcadia Holdings Inc. [Member] Landcadia Holdings Inc. [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Commissions and other fees Capital Markets And Asset Management Services, Commissions And Other Fees [Member] Capital Markets And Asset Management Services, Commissions And Other Fees [Member] Principal transactions Capital Markets And Asset Management Services, Principal Transactions [Member] Capital Markets And Asset Management Services, Principal Transactions [Member] Other revenues Capital Markets And Asset Management Services, Other [Member] Capital Markets And Asset Management Services, Other [Member] Accrued expenses and other liabilities Accounts Payable and Accrued Liabilities [Member] Charges to Jefferies for services provided 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 Quarterly dividend as percentage of net earnings Quarterly Dividend As Percentage Of Net Earnings Quarterly Dividend As Percentage Of Net Earnings Payments of dividends Dividends payable Dividends Payable 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 Payables-brokers, dealers and clearing organizations Financial instruments sold, not yet purchased Net gain on investment in hedge fund Related Party Transaction, Gain (Loss) on Transaction Related Party Transaction, Gain (Loss) on Transaction Number of public offering units owned Relate Party Transaction, Number of Public Offering Units Owned Relate Party Transaction, Number of Public Offering Units Owned Number of common stock per public offering unit (in shares) Relate Party Transaction, Number of Common Stock Per Public Offering Unit Relate Party Transaction, Number of Common Stock Per Public Offering Unit Number of public warrant per public offering unit Relate Party Transaction, Number of Public Warrant Per Public Offering Unit Relate Party Transaction, Number of Public Warrant Per Public Offering Unit Payments to acquire investments Payments to Acquire Investments Gain (loss) on sale of securities Debt and Equity Securities, Gain (Loss) Proceeds from sale of securities Proceeds from Sale of Available-for-sale Securities Net gains (losses) from our investments in JCP Fund V 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 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] Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Goodwill Gross costs - finite lived intangible assets Finite-Lived Intangible Assets, Gross Gross costs - indefinite lived intangible assets Indefinite Lived Intangible Assets Gross Indefinite lived Intangible asset Gross (before impairment). Total gross costs - intangible assets Intangible Assets, Gross (Excluding Goodwill) Accumulated amortization - finite lived intangible assets Finite-Lived Intangible Assets, Accumulated Amortization Net carrying amount - finite lived intangible assets Finite-Lived Intangible Assets, Net Net carrying amount - indefinite lived intangible assets Indefinite Lived Intangible Asset Net Cost (After Impairment) Indefinite Lived Intangible Asset Net Cost (After Impairment) Total net carrying amount - intangible assets Intangible Assets, Net (Excluding Goodwill) Weighted average remaining lives (years) Finite-Lived Intangible Asset, Useful Life Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Income Statement [Abstract] Revenues: Revenues [Abstract] Commissions and other fees Principal transactions Principal Transactions Revenue, Net 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 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 Occupancy and equipment rental Occupancy, Net Earnings before income taxes Income tax expense Income Tax Expense (Benefit) Net earnings 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 Accounting Standards Update 2016-18 Accounting Standards Update 2016-18 [Member] Member's paid-in capital Additional Paid-in Capital [Member] Tax Cuts and Jobs Act adjustment Tax Cuts And Jobs Act of 2017, Reclassification from Aoci to Additional Paid-in Capital Tax Effect Tax Cuts And Jobs Act of 2017, Reclassification from Aoci to Additional Paid-in Capital Tax Effect Net cash used in operating activities Cumulative effect of the adoption of the new revenue standard Cumulative Effect of New Accounting Principle in Period of Adoption 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 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, Aggregate Fair Value 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] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents ($1,094 and $7,514 at August 31, 2018 and November 30, 2017, respectively, related to consolidated VIEs) Cash and Cash Equivalents, at Carrying Value Financial instruments owned, at fair value, (including securities pledged of $12,868,364 and $10,842,051 at August 31, 2018 and November 30, 2017, respectively; and $381 and $38,044 at August 31, 2018 and November 30, 2017, 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 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 ($0 and $197 at August 31, 2018 and November 30, 2017, respectively, related to consolidated VIEs) 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 Other assets ($2 at both August 31, 2018 and November 30, 2017, related to consolidated VIEs) Other Assets Total assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Short-term borrowings (includes $0 and $23,324 at fair value at August 31, 2018 and November 30, 2017, respectively) 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 $1,004,822 and $722,108 at August 31, 2018 and November 30, 2017, 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 ($890 and $1,391 at August 31, 2018 and November 30, 2017, respectively, related to consolidated VIEs) Accounts Payable and Accrued Liabilities Long-term debt (includes $709,557 and $606,956 at fair value at August 31, 2018 and November 30, 2017, respectively) Long-term Debt Total liabilities Liabilities EQUITY Equity [Abstract] Member’s paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive 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 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 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 Hedge Funds, Equity Long (Short) [Member] Fixed Income and High Yield Hedge Funds High Yield Hedge Funds [Member] High Yield Hedge Funds. Fund of Funds Fund Of Funds [Member] Fund of Funds. Private equity funds Private Equity Funds [Member] Commodity Funds Commodity Funds [Member] Commodity Funds [Member] Multi-asset Funds Multi-asset Funds [Member] Multi-asset Funds [Member] 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 Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments 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. 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. Percentage of redeemable investments Redeemable Investments Investments redeemable within 60-90 days Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] 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. Jefferies Bache Limited Jefferies Bache Limited [Member] Jefferies Bache Limited [Member] Changes to presentation of Consolidated Statements of Cash Flows Changes To Presentation Of Consolidated Statements Of Cash Flows [Member] Changes To Presentation Of Consolidated Statements Of Cash Flows [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt instrument interest rate Debt Instrument, Interest Rate, Stated Percentage Payment to transfer defined benefit obligation and insurance contracts Defined Benefit Plan, Payment To Transfer Defined Benefit Obligation And Insurance Contracts Defined Benefit Plan, Payment To Transfer Defined Benefit Obligation And Insurance Contracts Consideration for release of indemnity relating to pension obligations Consideration For Release of Indemnity Relating To Pension Obligations Consideration For Release of Indemnity Relating To Pension Obligations Decrease of proceeds from short-term borrowings Increase of payments on short-term borrowings Loss Contingencies [Table] Loss Contingencies [Table] Jefferies Capital Partners LLC Jefferies Capital Partners Llc [Member] Jefferies capital partners, LLC. Other Investments Investments, Other [Member] Investments, Other [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Standby Letters of Credit Standby Letters of Credit [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Outstanding equity commitments Loan commitments outstanding to clients Loan Commitments Outstanding Loan commitments outstanding to clients. Fair value of derivative contracts approximated deemed to meet the definition of a guarantee 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 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] 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] 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] Loans and other receivables Fair Value, Option, Credit Risk, Gains (Losses) on Assets Financial Instruments Sold and Long-term Debt Changes in instrument specific credit risk Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Reclassification Adjustment from AOCI for Derecognition, after Tax 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] Securitization Vehicles Securitization Activity [Member] Securitization Activity [Member] Other Other Activity [Member] Other activity. 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] Fees, interest and other receivables Fees, Interest and Other Receivables [Member] Fees, Interest and Other Receivables [Member] Other secured financings Other Secured Financings [Member] Other Secured Financings [Member] Other liabilities Other Liabilities [Member] Assets Variable Interest Entity, Consolidated, Carrying Amount, Assets Liabilities Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Secured financing included in inventory and eliminated Vie Secured Financing Eliminated In Consolidation Secured financing held by The Company in Inventory and eliminated in consolidation. Commitments, Contingencies and Guarantees Commitments Contingencies and Guarantees [Text Block] Consolidation Consolidation, Policy [Policy Text Block] Investment Banking Revenues and Asset Management Fees Revenue from Contract with Customer [Policy Text Block] Accounting Standards to be Adopted in Future Periods and Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] 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] 5.125% Senior Notes Five Point One Two Five Percentage Senior Notes Due Two Thousand Eighteen [Member] 5.125% Senior Notes, due 2018. 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