Revenues from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2019	Aug. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 586,876	$ 633,210	$ 1,636,618	$ 1,903,938
Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	583,536	628,026	1,622,059	1,887,808
Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,340	5,184	14,559	16,130
Americas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	478,920	551,403	1,296,864	1,644,633
Americas | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	476,983	546,219	1,288,046	1,628,503
Americas | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,937	5,184	8,818	16,130
Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	90,293	62,914	286,346	203,103
Europe | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	88,890	62,914	280,605	203,103
Europe | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,403	0	5,741	0
Asia
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17,663	18,893	53,408	56,202
Asia | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17,663	18,893	53,408	56,202
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	167,528	159,693	483,771	471,683
Equities | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	167,528	159,693	483,771	471,683
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	3,475	3,007	10,072	10,511
Fixed income | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,475	3,007	10,072	10,511
Fixed income | Asset Management
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Investment banking - Capital markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	199,183	277,735	555,830	809,884
Investment banking - Capital markets | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	199,183	277,735	555,830	809,884
Investment banking - Capital markets | 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	213,350	187,591	572,386	595,730
Investment banking - Advisory | Capital Markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	213,350	187,591	572,386	595,730
Investment banking - Advisory | 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	3,340	5,184	14,559	16,130
Asset management | 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	$ 3,340	$ 5,184	$ 14,559	$ 16,130