Revenues from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 632,995	$ 602,335	$ 1,408,936	$ 1,049,742
Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	630,758	597,785	1,402,295	1,038,523
Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,237	4,550	6,641	11,219
Americas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	525,193	491,174	1,175,242	817,944
Americas | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	524,627	487,674	1,173,696	811,063
Americas | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	566	3,500	1,546	6,881
Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	69,753	92,560	152,615	196,053
Europe | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	68,082	91,510	147,520	191,715
Europe | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,671	1,050	5,095	4,338
Asia
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38,049	18,601	81,079	35,745
Asia | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38,049	18,601	81,079	35,745
Asia | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Equities
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	236,683	164,169	412,932	316,243
Equities | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	236,683	164,169	412,932	316,243
Equities | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Fixed income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,584	3,529	9,870	6,597
Fixed income | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,584	3,529	9,870	6,597
Fixed income | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Investment banking - Advisory
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	182,081	178,554	525,239	359,036
Investment banking - Advisory | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	182,081	178,554	525,239	359,036
Investment banking - Advisory | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Investment banking - Underwriting
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	205,410	251,533	454,254	356,647
Investment banking - Underwriting | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	205,410	251,533	454,254	356,647
Investment banking - Underwriting | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Asset management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,237	4,550	6,641	11,219
Asset management | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Asset management | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 2,237	$ 4,550	$ 6,641	$ 11,219