Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Aug. 31, 2018	Nov. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 325,280	$ 215,385
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	14,870,339	13,977,967
Derivative assets	175,428	163,833
Counterparty and Cash Collateral Netting	(3,331,143)	(3,254,216)
Securities received as collateral	0	103
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	8,128,200	8,171,929
Derivative liabilities	691,573	236,950
Counterparty and Cash Collateral Netting	(3,451,531)	(3,426,249)
Short-term borrowings	0	23,324
Long-term debt	709,557	606,956
Obligation to return securities received as collateral	0	103
Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,001,990	1,880,553
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,314,332	1,488,845
Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,296,503	3,287,336
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,377,087	1,689,347
CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	105,940	169,170
U.S. government and federal agency securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,922,558	1,308,673
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,127,608	1,430,737
Municipal securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	749,616	710,513
Sovereign obligations
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,986,160	2,417,459
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	2,472,290	2,173,635
Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,899,487	1,479,371
Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	815,365	520,534
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	70	105
Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	333,272	278,240
Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,504,481	1,667,885
Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	79,539	94,400
Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,145,240	1,152,310
Level 1
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	6,084,104	4,612,403
Derivative assets	6,644	160,168
Securities received as collateral		103
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	3,958,233	4,351,974
Derivative liabilities	4,976	247,919
Short-term borrowings		0
Long-term debt	0	0
Obligation to return securities received as collateral		103
Level 1 | Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,881,376	1,801,453
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,312,412	1,456,675
Level 1 | Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0	0
Level 1 | CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | U.S. government and federal agency securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,876,669	1,269,230
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,127,608	1,430,737
Level 1 | Municipal securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Sovereign obligations
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,319,415	1,381,552
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,513,237	1,216,643
Level 1 | Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0	0
Level 1 | Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0	0
Level 2
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	11,806,245	12,292,053
Derivative assets	3,496,790	3,248,586
Securities received as collateral		0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	7,598,608	7,226,002
Derivative liabilities	4,125,994	3,399,239
Short-term borrowings		23,324
Long-term debt	545,927	606,956
Obligation to return securities received as collateral		0
Level 2 | Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	72,569	57,091
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,507	32,122
Level 2 | Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,286,852	3,261,300
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,375,530	1,688,825
Level 2 | CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	82,339	139,166
Level 2 | U.S. government and federal agency securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	45,889	39,443
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0	0
Level 2 | Municipal securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	749,616	710,513
Level 2 | Sovereign obligations
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	666,745	1,035,907
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	958,998	956,992
Level 2 | Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,894,533	1,453,294
Level 2 | Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	791,449	508,115
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0	0
Level 2 | Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	263,967	217,111
Level 2 | Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,455,496	1,620,581
Level 2 | Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	946
Level 2 | Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,136,579	1,148,824
Level 3
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	311,133	327,727
Derivative assets	3,137	9,295
Securities received as collateral		0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	22,890	20,202
Derivative liabilities	12,134	16,041
Short-term borrowings		0
Long-term debt	163,630	0
Obligation to return securities received as collateral		0
Level 3 | Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	48,045	22,009
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	413	48
Level 3 | Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	9,651	26,036
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,557	522
Level 3 | CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	23,601	30,004
Level 3 | U.S. government and federal agency securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0	0
Level 3 | Municipal securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 3 | Sovereign obligations
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	55	0
Level 3 | Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	4,954	26,077
Level 3 | Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	23,916	12,419
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	70	105
Level 3 | Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	69,305	61,129
Level 3 | Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	48,985	47,304
Level 3 | Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	79,539	93,454
Level 3 | Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	8,661	3,486
Fair value based on net asset value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 325,300	$ 215,400