Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Feb. 29, 2020	Nov. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	$ 890,137	$ 570,310
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	17,007,249	15,793,064
Counterparty and Cash Collateral Netting	(2,717,442)	(1,432,806)
Securities purchased under agreements to resell		25,000
Securities received as collateral	15,004	9,500
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	9,877,182	10,532,460
Counterparty and Cash Collateral Netting	(2,849,172)	(1,631,787)
Short-term borrowings	20,164	20,981
Obligation to return securities received as collateral	15,004	9,500
Long-term debt	1,354,714	1,215,285
Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,604,461	2,601,820
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,132,054	2,767,526
Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,866,112	2,479,703
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,773,257	1,471,482
Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	118,277	144,306
U.S. government and federal agency securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,639,766	2,260,242
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,577,052	1,851,981
Municipal securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	775,960	742,326
Sovereign obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,747,245	2,735,853
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,878,491	2,304,540
Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,097,665	1,086,806
Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	445,933	430,170
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	301,912	346,410
Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,705,430	2,459,451
Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	597,609	397,551
Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	106,879	108,426
Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,820,886	1,609,691
Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	695,407	527,205
Fair value based on net asset value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investment	890,100	570,300
Level 1
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	6,438,252	5,759,575
Securities purchased under agreements to resell		0
Securities received as collateral	15,004	9,500
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	4,772,326	5,971,928
Short-term borrowings	0	0
Obligation to return securities received as collateral	15,004	9,500
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	3,343,000	2,325,116
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,124,882	2,755,601
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	1,541,590	2,101,624
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,577,052	1,851,981
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	1,552,798	1,330,026
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,070,355	1,363,475
Level 1 | Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	0	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	864	2,809
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	37	871
Level 2
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	12,940,782	11,159,143
Securities purchased under agreements to resell		0
Securities received as collateral	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	7,807,005	6,085,937
Short-term borrowings	20,164	20,981
Obligation to return securities received as collateral	0	0
Long-term debt	811,251	735,216
Level 2 | Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	157,818	218,403
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	2,897	7,438
Level 2 | Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,841,022	2,472,213
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,772,490	1,471,142
Level 2 | Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	97,325	124,225
Level 2 | U.S. government and federal agency securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	98,176	158,618
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	775,960	742,326
Level 2 | Sovereign obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,194,447	1,405,827
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	808,136	941,065
Level 2 | Residential mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	1,080,695	1,069,066
Level 2 | Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	441,669	424,060
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	260,009	303,847
Level 2 | Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	2,651,109	2,395,211
Level 2 | Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	3,290,943	1,812,659
Level 2 | Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	51,609	32,688
Level 2 | Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	1,813,027	1,600,228
Level 2 | Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	3,410,455	2,066,064
Level 3
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	345,657	307,152
Securities purchased under agreements to resell		25,000
Securities received as collateral	0	0
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	147,023	106,382
Short-term borrowings	0	0
Obligation to return securities received as collateral	0	0
Long-term debt	543,463	480,069
Level 3 | Corporate equity securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	103,643	58,301
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	4,275	4,487
Level 3 | Corporate debt securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	25,090	7,490
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	767	340
Level 3 | Collateralized debt obligations and collateralized loan obligations
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	20,952	20,081
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	16,970	17,740
Level 3 | Commercial mortgage-backed securities
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	4,264	6,110
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	41,903	42,563
Level 3 | Loans and other receivables
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	54,321	64,240
Level 3 | Derivative assets
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	23,244	14,889
Level 3 | Investments at fair value
Financial instruments owned:
Total financial instruments owned, excluding Investments at fair value based on NAV	55,270	75,738
Level 3 | Loans
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	7,859	9,463
Level 3 | Derivative liabilities
Financial instruments sold, not yet purchased:
Total financial instruments sold, not yet purchased	$ 134,087	$ 92,057