Common Share and Earnings Per Common Share (Earnings Per Share Computation) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019
Numerator for earnings per share:
Net income attributable to Jefferies Financial Group Inc. common shareholders	$ 304,409	$ 48,477	$ 462,338	$ 764,052
Allocation of earnings to participating securities	(1,945)	(316)	(2,921)	(4,667)
Net income attributable to Jefferies Financial Group Inc. common shareholders for basic earnings per share	302,464	48,161	459,417	759,385
Adjustment to allocation of earnings to participating securities related to diluted shares	17	(7)	5	29
Mandatorily redeemable convertible preferred share dividends	1,404	0	4,230	3,827
Net income attributable to Jefferies Financial Group Inc. common shareholders for diluted earnings per share	$ 303,885	$ 48,154	$ 463,652	$ 763,241
Denominator for earnings per share:
Weighted average common shares outstanding (in shares)	263,062,000	296,834,000	273,035,000	298,322,000
Denominator for basic earnings per share – weighted average shares (in shares)	280,695,000	310,288,000	289,959,000	310,838,000
Mandatorily redeemable convertible preferred shares (in shares)	4,441,000	0	4,441,000	4,162,000
Denominator for diluted earnings per share (in shares)	285,136,000	311,897,000	294,875,000	317,181,000
Weighted average shares of participating securities (in shares)	1,807,800	2,018,000	1,851,900	1,910,700
Restricted stock with future service required
Denominator for earnings per share:
Weighted average shares of restricted stock outstanding with future service required (in shares)	(1,787,000)	(2,008,000)	(1,837,000)	(1,903,000)
Restricted stock units with no future service required
Denominator for earnings per share:
Weighted average RSUs outstanding with no future service required (in shares)	19,420,000	15,462,000	18,761,000	14,419,000
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	1,609,000	475,000	2,181,000