Fair Value Disclosures (Schedule Of Assets And Liabilities Measured On Recurring Basis At Fair Value) (Details) - USD ($) $ in Thousands	Feb. 29, 2020	Nov. 30, 2019
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	$ 17,498,867	$ 16,308,807
Counterparty and cash collateral netting, assets	(2,717,442)	(1,433,197)
Securities purchased under agreements to resell		25,000
Securities received as collateral	15,004	9,500
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	9,879,387	10,532,460
Counterparty and Cash Collateral Netting, liabilities	(2,849,172)	(1,632,178)
Short-term borrowings	20,164	20,981
Long-term debt	1,354,714	1,215,285
Obligation to return securities received as collateral	15,004	9,500
Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	6,601,025	5,941,623
Securities purchased under agreements to resell		0
Securities received as collateral	15,004	9,500
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	4,772,326	5,971,928
Short-term borrowings	0	0
Long-term debt	0	0
Obligation to return securities received as collateral	15,004	9,500
Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	13,020,968	11,245,763
Securities purchased under agreements to resell		0
Securities received as collateral	0	0
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	7,809,210	6,086,328
Short-term borrowings	20,164	20,981
Long-term debt	811,251	735,216
Obligation to return securities received as collateral	0	0
Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	594,316	554,618
Securities purchased under agreements to resell		25,000
Securities received as collateral	0	0
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	147,023	106,382
Short-term borrowings	0	0
Long-term debt	543,463	480,069
Obligation to return securities received as collateral	0	0
Fair value measured at NAV
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative investments	898,114	586,934
Corporate equity securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	3,767,274	2,783,993
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	2,132,054	2,767,526
Obligation to return securities received as collateral	5,096	0
Corporate equity securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	3,505,773	2,507,164
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	2,124,882	2,755,601
Corporate equity securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	157,818	218,403
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	2,897	7,438
Corporate equity securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	103,683	58,426
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	4,275	4,487
Corporate debt securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	2,866,145	2,479,735
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,773,257	1,471,482
Obligation to return securities received as collateral	0	0
Corporate debt securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
Corporate debt securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	2,841,055	2,472,245
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,772,490	1,471,142
Corporate debt securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	25,090	7,490
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	767	340
Collateralized debt obligations and collateralized loan obligations
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	127,109	153,013
Collateralized debt obligations and collateralized loan obligations | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Collateralized debt obligations and collateralized loan obligations | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	97,325	124,225
Collateralized debt obligations and collateralized loan obligations | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	29,784	28,788
U.S. government and federal agency securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	1,639,766	2,260,242
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,577,052	1,851,981
U.S. government and federal agency securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	1,541,590	2,101,624
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,577,052	1,851,981
U.S. government and federal agency securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	98,176	158,618
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
U.S. government and federal agency securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
Municipal securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	775,960	742,326
Liabilities:
Obligation to return securities received as collateral	0	0
Municipal securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Municipal securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	775,960	742,326
Municipal securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Sovereign obligations
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	2,747,245	2,735,853
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,878,491	2,304,540
Obligation to return securities received as collateral	0	0
Sovereign obligations | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	1,552,798	1,330,026
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,070,355	1,363,475
Sovereign obligations | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	1,194,447	1,405,827
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	808,136	941,065
Sovereign obligations | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
Residential mortgage-backed securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	1,097,665	1,086,806
Residential mortgage-backed securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Residential mortgage-backed securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	1,080,695	1,069,066
Residential mortgage-backed securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	16,970	17,740
Commercial mortgage-backed securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	445,933	430,170
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	35	35
Commercial mortgage-backed securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
Commercial mortgage-backed securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	441,669	424,060
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
Commercial mortgage-backed securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	4,264	6,110
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	35	35
Other asset-backed securities
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	301,912	346,410
Other asset-backed securities | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Other asset-backed securities | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	260,009	303,847
Other asset-backed securities | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	41,903	42,563
Loans and other receivables
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	2,794,346	2,574,631
Liabilities:
Obligation to return securities received as collateral	0	0
Loans and other receivables | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Loans and other receivables | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	2,691,103	2,460,551
Loans and other receivables | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	103,243	114,080
Derivatives, assets
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	637,768	418,408
Derivatives, assets | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	864	2,809
Derivatives, assets | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	3,331,102	1,833,907
Derivatives, assets | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	23,244	14,889
Investments at fair value
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	236,116	238,100
Investments at fair value | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
Investments at fair value | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	51,609	32,688
Investments at fair value | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	184,507	205,412
FXCM term loan
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	61,628	59,120
FXCM term loan | Level 1
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
FXCM term loan | Level 2
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	0	0
FXCM term loan | Level 3
Assets:
Financial instruments owned, at fair value, excluding investments at fair value based on NAV	61,628	59,120
Loans
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,820,886	1,609,691
Loans | Level 1
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	0	0
Loans | Level 2
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	1,813,027	1,600,228
Loans | Level 3
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	7,859	9,463
Derivatives, liabilities
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	697,612	527,205
Derivatives, liabilities | Level 1
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	37	871
Derivatives, liabilities | Level 2
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	3,412,660	2,066,455
Derivatives, liabilities | Level 3
Liabilities:
Financial instruments sold, not yet purchased, at fair value:	$ 134,087	$ 92,057