Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Feb. 28, 2021	Nov. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 1,017,822	$ 955,984
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	17,553,054	16,730,068
Counterparty and Cash Collateral Netting	(2,604,607)	(1,556,136)
Securities received as collateral	0	7,517
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	12,361,542	10,017,522
Counterparty and Cash Collateral Netting	(2,997,103)	(1,798,659)
Short-term borrowings	0	5,067
Other secured financings	2,168	1,543
Obligation to return securities received as collateral, at fair value	0	7,517
Long-term debt	1,784,157	1,712,245
Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,829,205	2,465,396
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,130,512	2,059,921
Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,458,605	2,977,347
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,826,029	1,237,772
Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	117,548	74,668
U.S. government and federal agency securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,559,363	2,931,678
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,618,198	2,609,660
Municipal securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	292,604	453,881
Sovereign obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,468,214	2,553,688
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,360,608	1,675,511
Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,902,515	1,122,675
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased		477
Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	39,684	738,294
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	35	35
Other asset-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	124,550	183,606
Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,178,972	2,687,788
Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	529,923	467,817
Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	51,871	73,230
Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,341,222	1,793,081
Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,084,938	641,065
Fair value based on net asset value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	1,017,800	956,000
Level 1
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	6,846,005	7,135,334
Securities received as collateral		7,517
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	6,089,285	5,707,423
Short-term borrowings		0
Other secured financings	0	0
Obligation to return securities received as collateral, at fair value		7,517
Long-term debt	0	0
Level 1 | Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,687,871	2,331,440
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,124,994	2,046,441
Level 1 | Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 1 | Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total 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:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,485,813	2,840,025
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,618,198	2,609,660
Level 1 | Municipal securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Sovereign obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,668,975	1,962,346
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,343,920	1,050,771
Level 1 | Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased		0
Level 1 | Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 1 | Other asset-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,346	1,523
Level 1 | Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 1 | Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 1 | Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,173	551
Level 2
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	12,946,792	10,771,762
Securities received as collateral		0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	8,903,492	6,039,818
Short-term borrowings		5,067
Other secured financings	0	0
Obligation to return securities received as collateral, at fair value		0
Long-term debt	1,061,042	1,036,217
Level 2 | Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	58,056	58,159
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,075	9,046
Level 2 | Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,451,794	2,954,201
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,824,458	1,237,631
Level 2 | Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	91,654	64,155
Level 2 | U.S. government and federal agency securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	73,550	91,653
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 2 | Municipal securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	292,604	453,881
Level 2 | Sovereign obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	799,239	591,342
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,016,688	624,740
Level 2 | Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,880,823	1,100,849
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased		477
Level 2 | Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	37,013	736,291
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 2 | Other asset-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	63,956	103,611
Level 2 | Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,099,917	2,610,746
Level 2 | Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,091,787	2,000,752
Level 2 | Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	6,399	6,122
Level 2 | Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,326,306	1,776,446
Level 2 | Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	3,734,965	2,391,478
Level 3
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	364,864	379,108
Securities received as collateral		0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	365,868	68,940
Short-term borrowings		0
Other secured financings	2,168	1,543
Obligation to return securities received as collateral, at fair value		0
Long-term debt	723,115	676,028
Level 3 | Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	83,278	75,797
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	4,443	4,434
Level 3 | Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	6,811	23,146
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,571	141
Level 3 | Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	25,894	10,513
Level 3 | U.S. government and federal agency securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 3 | Municipal securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Level 3 | Sovereign obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	0	0
Level 3 | Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	21,692	21,826
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased		0
Level 3 | Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,671	2,003
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	35	35
Level 3 | Other asset-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	60,594	79,995
Level 3 | Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	79,055	77,042
Level 3 | Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	39,397	21,678
Level 3 | Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	45,472	67,108
Level 3 | Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	14,916	16,635
Level 3 | Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	$ 344,903	$ 47,695