Revenues from Contracts with Customers - Components of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 28, 2019	Feb. 28, 2018
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 447,394	$ 599,509
Revenues	1,054,872	1,086,595
Commissions and other fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	147,326	147,902
Investment banking
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	285,596	439,991
Asset management fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	6,669	4,930
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,803	6,686
Principal transactions
Disaggregation of Revenue [Line Items]
Revenues	234,298	217,473
Interest
Disaggregation of Revenue [Line Items]
Revenues	360,975	257,816
Other
Disaggregation of Revenue [Line Items]
Revenues	$ 12,205	$ 11,797