Common Share and Earnings Per Common Share (Earnings Per Share Computation) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Numerator for earnings per share:
Net income attributable to Jefferies Financial Group Inc. common shareholders	$ 44,919	$ 670,764	$ 157,929	$ 715,575
Allocation of earnings to participating securities	(288)	(4,086)	(988)	(4,241)
Net income attributable to Jefferies Financial Group Inc. common shareholders for basic earnings per share	44,631	666,678	156,941	711,334
Adjustment to allocation of earnings to participating securities related to diluted shares	(9)	43	(11)	34
Mandatorily redeemable convertible preferred share dividends	0	1,276	0	2,552
Net income attributable to Jefferies Financial Group Inc. common shareholders for diluted earnings per share	$ 44,622	$ 667,997	$ 156,930	$ 713,920
Denominator for earnings per share:
Weighted average common shares outstanding (in shares)	269,362,000	293,600,000	278,022,000	299,067,000
Denominator for basic earnings per share – weighted average shares (in shares)	286,764,000	307,010,000	294,589,000	311,108,000
Mandatorily redeemable convertible preferred shares (in shares)	0	4,162,000	0	4,162,000
Denominator for diluted earnings per share (in shares)	286,764,000	312,527,000	295,301,000	317,736,000
Weighted average shares of participating securities (in shares)	1,846,400	1,881,600	1,874,100	1,856,400
Restricted stock with future service required
Denominator for earnings per share:
Weighted average shares of restricted stock outstanding with future service required (in shares)	(1,832,000)	(1,873,000)	(1,862,000)	(1,851,000)
Restricted stock units with no future service required
Denominator for earnings per share:
Weighted average RSUs outstanding with no future service required (in shares)	19,234,000	15,283,000	18,429,000	13,892,000
Stock options
Denominator for earnings per share:
Dilutive effect of share-based payment awards (in shares)	0	0	0	0
Restricted stock units | Senior executive compensation plan awards
Denominator for earnings per share:
Dilutive effect of share-based payment awards (in shares)	0	1,355,000	712,000	2,466,000