| Cover - USD ($) | 12 Months Ended | ||
| Nov. 30, 2019 | Jan. 17, 2020 | May 31, 2019 | |
| Cover Page. [Abstract] | |||
| Document Type | 10-K/A | ||
| Document Annual Report | true | ||
| Document Period End Date | Nov. 30, 2019 | ||
| Document Transition Report | false | ||
| Entity File Number | 1-5721 | ||
| Entity Registrant Name | JEFFERIES FINANCIAL GROUP INC. | ||
| Entity Incorporation, State or Country Code | NY | ||
| Entity Tax Identification Number | 13-2615557 | ||
| Entity Address, Address Line One | 520 Madison Avenue | ||
| Entity Address, City or Town | New York, | ||
| Entity Address, State or Province | NY | ||
| Entity Address, Postal Zip Code | 10022 | ||
| City Area Code | 212 | ||
| Local Phone Number | 460-1900 | ||
| Title of 12(b) Security | Common Shares, par value $1 per share | ||
| Trading Symbol | JEF | ||
| Security Exchange Name | NYSE | ||
| Entity Well-known Seasoned Issuer | Yes | ||
| Entity Voluntary Filers | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Filer Category | Large Accelerated Filer | ||
| Entity Small Business | false | ||
| Entity Emerging Growth Company | false | ||
| Entity Shell Company | false | ||
| Entity Public Float | $ 4,668,438,072 | ||
| Entity Common Stock, Shares Outstanding | 287,939,689 | ||
| Documents Incorporated by Reference | Certain portions of the registrant's Definitive Proxy Statement pursuant to Regulation 14A of the Securities Exchange Act of 1934 in connection with the 2020 Annual Meeting of Shareholders are incorporated by reference into Part III of this Form 10-K. | ||
| Amendment Flag | true | ||
| Amendment Description | We are filing this Amendment No. 1 to our Annual Report on Form 10-K for the fiscal year ended November 30, 2019, solely to add National Beef Packing Company, LLC financial statements as of December 28, 2019 and December 29, 2018 and for the years ended December 28, 2019, December 29, 2018 and December 30, 2017 and Berkadia Commercial Mortgage Holding LLC financial statements as of December 31, 2019 and 2018, and for the years ended December 31, 2019, 2018 and 2017. | ||
| Document Fiscal Year Focus | 2019 | ||
| Document Fiscal Period Focus | FY | ||
| Current Fiscal Year End Date | --11-30 | ||
| Entity Central Index Key | 0000096223 |
