Accounting Developments - Schedule of New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2018	Aug. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment banking	$ 465,326	$ 475,702	$ 1,405,614	$ 1,235,586
Total revenues	1,088,285	1,048,331	3,331,689	3,097,083
Net revenues	777,615	800,692	2,421,418	2,375,499
Underwriting costs	20,528	0	47,832	0
Technology and communications	76,877	72,440	222,335	205,425
Business development	39,733	23,125	124,233	72,223
Professional services	35,316	25,007	101,715	83,544
Other	18,723	22,318	54,888	62,670
Total non-compensation expenses	262,481	215,495	761,954	639,228
Total non-interest expenses	690,514	$ 678,428	2,089,714	$ 2,012,855
ASC 606 Impact | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment banking	36,319		101,146
Total revenues	36,319		101,146
Net revenues	36,319		101,146
Underwriting costs	20,528		47,832
Technology and communications	97		311
Business development	14,946		50,187
Professional services	401		1,968
Other	347		848
Total non-compensation expenses	36,319		101,146
Total non-interest expenses	36,319		101,146
Adjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment banking	429,007		1,304,468
Total revenues	1,051,966		3,230,543
Net revenues	741,296		2,320,272
Underwriting costs	0		0
Technology and communications	76,780		222,024
Business development	24,787		74,046
Professional services	34,915		99,747
Other	18,376		54,040
Total non-compensation expenses	226,162		660,808
Total non-interest expenses	$ 654,195		$ 1,988,568