Revenues from Contracts with Customers - Components of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 821,763	$ 586,876	$ 2,230,699	$ 1,636,618
Principal transactions	560,665	148,873	1,399,850	632,002
Revenues from arrangements with strategic partners	5,159	880	14,814	1,791
Interest	195,960	383,596	702,569	1,163,022
Other	11,526	21,406	(6,020)	77,563
Total revenues	1,595,073	1,141,631	4,341,912	3,510,996
Commissions and other fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	204,313	171,003	627,115	493,843
Investment banking
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	615,837	412,533	1,595,330	1,128,216
Asset management fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 1,613	$ 3,340	$ 8,254	$ 14,559