Revenues from Contracts with Customers - Disaggregation 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
Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	820,150	583,536	2,222,445	1,622,059
Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,613	3,340	8,254	14,559
Americas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	684,685	478,920	1,859,927	1,296,864
Americas | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	684,441	476,983	1,858,137	1,288,046
Americas | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	244	1,937	1,790	8,818
Europe
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	91,501	90,293	244,116	286,346
Europe | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	90,132	88,890	237,652	280,605
Europe | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,369	1,403	6,464	5,741
Asia
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	45,577	17,663	126,656	53,408
Asia | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	45,577	17,663	126,656	53,408
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	201,157	167,528	614,089	483,771
Equities | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	201,157	167,528	614,089	483,771
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	3,156	3,475	13,026	10,072
Fixed income | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,156	3,475	13,026	10,072
Fixed income | 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	171,438	213,350	696,677	572,386
Investment banking - Advisory | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	171,438	213,350	696,677	572,386
Investment banking - Advisory | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - Underwriting
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	444,399	199,183	898,653	555,830
Investment banking - Underwriting | Investment Banking and Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	444,399	199,183	898,653	555,830
Investment banking - Underwriting | 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	1,613	3,340	8,254	14,559
Asset management | Investment Banking and 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	$ 1,613	$ 3,340	$ 8,254	$ 14,559