Derivative Financial Instruments (Unrealized and Realized Gains (Losses) on Derivative Contracts (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in Interest expense of Jefferies Group	$ 2,468	$ (467)	$ 1,764	$ (2,445)
Unrealized and realized gains (losses)	(82,721)	(84,495)	131,411	(296,143)
Net investment hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on net investment hedges recognized in other comprehensive income (loss)	(393)	0	(393)	0
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	(35,462)	(89,864)	(40,630)	(193,715)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	4,418	(1,839)	2,534	269
Foreign exchange contracts \| Net investment hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on net investment hedges recognized in other comprehensive income (loss)	(393)	0	(393)	0
Equity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	(32,782)	2,236	113,253	(118,354)
Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	(18,716)	2,285	42,049	4,057
Credit contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized and realized gains (losses)	(179)	2,687	14,205	11,600
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in Interest expense of Jefferies Group	834	28,052	47,303	69,843
Long-term debt
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in Interest expense of Jefferies Group	$ 1,634	$ (28,519)	$ (45,539)	$ (72,288)

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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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Amount before tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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