Net Capital Requirements - Net Capital, Adjusted and Excess Net Capital (Detail) - USD ($) $ in Thousands	Nov. 30, 2016	Nov. 30, 2015
Net Capital Requirements [Line Items]
Amount of restricted net assets for consolidated subsidiaries	$ 4,833,000	$ 5,202,700
Jefferies [Member]
Net Capital Requirements [Line Items]
Net Capital	1,467,729
Excess Net Capital	1,398,748
Jefferies Execution [Member]
Net Capital Requirements [Line Items]
Net Capital	8,260
Excess Net Capital	$ 8,010

Net Capital Requirements [Line Items]

No definition available.

Name:	jef_NetCapitalRequirementsLineItems
Namespace Prefix:	jef_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of net capital in excess of the alternative minimum required net capital.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

+ Details

Name:	us-gaap_AlternativeExcessNetCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e)(3)(ii))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_AmountOfRestrictedNetAssetsForConsolidatedAndUnconsolidatedSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Net capital is equal to the net worth of the broker dealer, less certain items such as exchange memberships, carrying value of securities not readily marketable, haircuts on marketable securities in proprietary accounts, furniture and equipment and other illiquid assets as defined.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

+ Details

Name:	us-gaap_NetCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=jef_JefferiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=jef_JefferiesExecutionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: