Revenues from Contracts with Customers - Components of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Nov. 30, 2020	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers:									$ 3,333,939	$ 2,222,257	$ 2,594,887
Principal transactions									1,867,013	769,258	524,296
Revenues from third-parties with strategic relationships pursuant to arrangements									19,507	3,066	0
Interest									894,215	1,496,529	1,207,095
Other									37,632	93,422	103,354
Total revenues	$ 1,810,394	$ 1,595,073	$ 1,267,283	$ 1,479,556	$ 1,073,536	$ 1,141,631	$ 1,314,493	$ 1,054,872	6,152,306	4,584,532	4,429,632
Commissions and other fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers:									823,258	676,309	663,470
Investment banking
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers:									2,501,494	1,528,729	1,910,203
Asset management fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers:									$ 9,187	$ 17,219	$ 21,214