Revenues from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 602,527	$ 671,219	$ 1,049,921	$ 1,270,728
Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	597,977	665,203	1,038,702	1,259,782
Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,550	6,016	11,219	10,946
Americas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	491,366	572,376	818,123	1,093,230
Americas | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	487,866	566,360	811,242	1,082,284
Americas | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,500	6,016	6,881	10,946
Europe
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	92,560	78,861	196,053	140,189
Europe | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	91,510	78,861	191,715	140,189
Europe | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,050	0	4,338	0
Asia
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	18,601	19,982	35,745	37,309
Asia | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	18,601	19,982	35,745	37,309
Asia | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Equities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	164,361	160,360	316,422	311,990
Equities | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	164,361	160,360	316,422	311,990
Equities | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Fixed Income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,529	4,546	6,597	7,504
Fixed Income | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,529	4,546	6,597	7,504
Fixed Income | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - Capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	251,533	283,315	356,647	532,149
Investment banking - Capital markets | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	251,533	283,315	356,647	532,149
Investment banking - Capital markets | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - Advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	178,554	216,982	359,036	408,139
Investment banking - Advisory | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	178,554	216,982	359,036	408,139
Investment banking - Advisory | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Asset management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,550	6,016	11,219	10,946
Asset management | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Asset management | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 4,550	$ 6,016	$ 11,219	$ 10,946