Accounting Developments - Schedule of New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 28, 2018	Feb. 28, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment banking	$ 439,991	$ 408,021
Total revenues	1,086,595	1,009,797
Net revenues	821,246	795,513
Underwriting costs	14,275	0
Technology and communications	69,077	65,507
Business development	42,107	22,632
Professional services	30,408	32,124
Other	18,598	19,206
Total non-compensation expenses	242,875	211,142
Total non-interest expenses	698,508	$ 671,314
ASC 606 Impact | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment banking	32,485
Total revenues	32,485
Net revenues	32,485
Underwriting costs	14,275
Technology and communications	103
Business development	17,243
Professional services	711
Other	153
Total non-compensation expenses	32,485
Total non-interest expenses	32,485
Adjusted | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment banking	407,506
Total revenues	1,054,110
Net revenues	788,761
Underwriting costs	0
Technology and communications	68,974
Business development	24,864
Professional services	29,697
Other	18,445
Total non-compensation expenses	210,390
Total non-interest expenses	$ 666,023