Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	May 31, 2019	Nov. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 566,134	$ 322,909
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	15,529,750	16,076,617
Derivative assets	323,443	130,610
Counterparty and Cash Collateral Netting	(2,193,408)	(2,412,486)
Securities purchased under agreements to resell	25,000	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	10,113,390	9,478,944
Derivative liabilities	554,243	1,127,651
Counterparty and Cash Collateral Netting	(2,365,653)	(2,511,605)
Long-term debt	819,509	686,170
Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,312,698	2,077,666
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	2,669,887	1,686,515
Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,985,491	2,692,664
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,920,135	1,506,140
CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	140,035	98,764
U.S. government and federal agency securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,620,643	1,846,206
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,236,461	1,384,295
Municipal securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	963,607	894,253
Sovereign obligations
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,886,412	2,812,965
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	2,198,171	2,396,337
Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,177,227	2,183,232
Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	417,427	830,292
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	724
Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	310,750	292,556
Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,204,126	2,103,578
Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	187,891	113,831
Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,533,769	1,378,006
Level 1
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	5,503,182	5,479,301
Derivative assets	9,729	12,186
Securities purchased under agreements to resell	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	5,254,017	4,831,079
Derivative liabilities	24,578	26,471
Long-term debt	0	0
Level 1 | Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,121,270	1,907,945
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	2,664,846	1,685,071
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	1,505,882	1,789,614
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,236,461	1,384,295
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	1,866,301	1,769,556
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,328,132	1,735,242
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
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	11,853,333	12,673,061
Derivative assets	2,498,708	2,524,988
Securities purchased under agreements to resell	0
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	7,158,845	7,125,036
Derivative liabilities	2,839,455	3,585,249
Long-term debt	582,947	485,425
Level 2 | Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	132,121	118,681
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	4,820	1,444
Level 2 | Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,978,062	2,683,180
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,919,466	1,505,618
Level 2 | CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	123,840	72,949
Level 2 | U.S. government and federal agency securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	114,761	56,592
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	963,607	894,253
Level 2 | Sovereign obligations
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,020,111	1,043,409
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	870,039	661,095
Level 2 | Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	1,159,961	2,163,629
Level 2 | Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	404,897	819,406
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	724
Level 2 | Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	267,565	239,381
Level 2 | Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	2,105,642	2,056,593
Level 2 | Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	84,058	0
Level 2 | Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	1,524,341	1,371,630
Level 3
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	366,643	336,741
Derivative assets	8,414	5,922
Securities purchased under agreements to resell	25,000
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	66,181	34,434
Derivative liabilities	55,863	27,536
Long-term debt	236,562	200,745
Level 3 | Corporate equity securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	59,307	51,040
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	221	0
Level 3 | Corporate debt securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	7,429	9,484
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	669	522
Level 3 | CDOs and CLOs
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	16,195	25,815
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	0	0
Level 3 | Residential mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	17,266	19,603
Level 3 | Commercial mortgage-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	12,530	10,886
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	0
Level 3 | Other asset-backed securities
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	43,185	53,175
Level 3 | Loans and other receivables
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	98,484	46,985
Level 3 | Investments at fair value
Financial instruments owned:
Financial instruments owned, excluding Investments at fair value based on NAV	103,833	113,831
Level 3 | Loans
Financial instruments sold, not yet purchased:
Financial instruments sold, not yet purchased, at fair value	9,428	6,376
Fair value based on net asset value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 566,100	$ 322,900