Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2014	Nov. 30, 2013
Financial instruments owned:
Corporate equity securities	$ 2,359,225	$ 2,098,597
Corporate debt securities	3,203,168	2,982,768
Collateralized debt obligations	332,605	219,311
U.S. government and federal agency securities	2,251,250	2,333,610
Municipal securities	690,649	664,054
Sovereign obligations	2,558,365	2,348,488
Loans and other receivables	1,564,688	1,349,128
Derivatives	253,184	261,093
Investments at fair value	123,432	101,282
Physical commodities	47,166	37,888
Total financial instruments owned	17,143,518	16,650,043
Cash and cash equivalents	3,958,288	3,561,119
Investments in managed funds	75,369	57,285
Cash and securities segregated and on deposit for regulatory purposes	3,288,517	3,616,602
Securities received as collateral	126,106	11,063
Total Level 3 assets
Financial instruments sold, not yet purchased:
Corporate equity securities	1,684,304	1,823,299
Corporate debt securities	1,513,621	1,346,078
U.S. government and federal agency securities	1,554,835	1,324,326
Municipal securities
Sovereign obligations	2,233,386	1,831,357
Loans	903,856	695,300
Derivatives	226,288	180,079
Physical commodities	39,173	36,483
Total financial instruments sold, not yet purchased	8,172,300	7,271,613
Obligation to return securities received as collateral	126,106	11,063
Other secured financings	20,288	39,711
Embedded conversion option	3,895	9,574
Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	3,096,902	3,037,760
Financial instruments sold, not yet purchased:
Mortgage- and asset-backed securities, liabilities	16,837	34,691
Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	603,837	1,147,978
Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	59,047	68,086
Level 1 [Member]
Financial instruments owned:
Corporate equity securities	1,997,684	1,913,220
Corporate debt securities
Collateralized debt obligations
U.S. government and federal agency securities	2,176,254	2,293,221
Municipal securities
Sovereign obligations	1,540,017	1,458,803
Loans and other receivables
Derivatives	87,612	40,952
Investments at fair value
Physical commodities
Total financial instruments owned	5,801,567	5,706,196
Cash and cash equivalents	3,958,288	3,561,119
Investments in managed funds
Cash and securities segregated and on deposit for regulatory purposes	3,288,517	3,616,602
Securities received as collateral	126,106	11,063
Total Level 3 assets
Financial instruments sold, not yet purchased:
Corporate equity securities	1,632,106	1,782,903
Corporate debt securities
U.S. government and federal agency securities	1,554,835	1,324,326
Sovereign obligations	1,517,111	1,360,269
Loans
Derivatives	75,585	43,829
Physical commodities
Total financial instruments sold, not yet purchased	4,779,637	4,511,327
Obligation to return securities received as collateral	126,106	11,063
Other secured financings
Embedded conversion option
Level 1 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets
Financial instruments sold, not yet purchased:
Mortgage- and asset-backed securities, liabilities
Level 1 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets
Level 1 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets
Level 2 [Member]
Financial instruments owned:
Corporate equity securities	345,139	175,493
Corporate debt securities	3,171,520	2,957,102
Collateralized debt obligations	290,292	182,095
U.S. government and federal agency securities	74,996	40,389
Municipal securities	690,649	664,054
Sovereign obligations	1,018,348	889,685
Loans and other receivables	1,426,045	1,203,238
Derivatives	2,813,166	2,472,237
Investments at fair value	5,361	40
Physical commodities	47,166	37,888
Total financial instruments owned	13,500,816	12,740,374
Cash and cash equivalents
Investments in managed funds	19,250
Cash and securities segregated and on deposit for regulatory purposes
Securities received as collateral
Total Level 3 assets
Financial instruments sold, not yet purchased:
Corporate equity securities	52,160	40,358
Corporate debt securities	1,510,841	1,346,078
U.S. government and federal agency securities
Municipal securities
Sovereign obligations	716,275	471,088
Loans	872,322	672,838
Derivatives	2,881,585	2,480,463
Physical commodities	39,173	36,483
Total financial instruments sold, not yet purchased	6,089,193	5,081,999
Obligation to return securities received as collateral
Other secured financings		31,000
Embedded conversion option	3,895	9,574
Level 2 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	3,024,940	2,932,268
Financial instruments sold, not yet purchased:
Mortgage- and asset-backed securities, liabilities	16,837	34,691
Level 2 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	579,591	1,130,410
Level 2 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	13,603	55,475
Level 3 [Member]
Financial instruments owned:
Corporate equity securities	16,402	9,884
Corporate debt securities	31,648	25,666
Collateralized debt obligations	42,313	37,216
U.S. government and federal agency securities
Municipal securities
Sovereign obligations
Loans and other receivables	138,643	145,890
Derivatives	913	1,493
Investments at fair value	118,071	101,242
Physical commodities
Total financial instruments owned	489,642	457,062
Cash and cash equivalents
Investments in managed funds	56,119	57,285
Cash and securities segregated and on deposit for regulatory purposes
Securities received as collateral
Total Level 3 assets	545,761	514,347
Financial instruments sold, not yet purchased:
Corporate equity securities	38	38
Corporate debt securities	2,780
U.S. government and federal agency securities
Municipal securities
Sovereign obligations
Loans	31,534	22,462
Derivatives	16,195	8,398
Physical commodities
Total financial instruments sold, not yet purchased	50,547	30,898
Obligation to return securities received as collateral
Other secured financings	20,288	8,711
Embedded conversion option
Level 3 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	71,962	105,492
Financial instruments sold, not yet purchased:
Mortgage- and asset-backed securities, liabilities
Level 3 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	24,246	17,568
Level 3 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	45,444	12,611
Counterparty and Cash Collateral Netting [Member]
Financial instruments owned:
Corporate equity securities
Corporate debt securities
Collateralized debt obligations
U.S. government and federal agency securities
Municipal securities
Sovereign obligations
Loans and other receivables
Derivatives	(2,648,507)	(2,253,589)
Investments at fair value
Physical commodities
Total financial instruments owned	(2,648,507)	(2,253,589)
Cash and cash equivalents
Investments in managed funds
Cash and securities segregated and on deposit for regulatory purposes
Securities received as collateral
Total Level 3 assets
Financial instruments sold, not yet purchased:
Corporate equity securities
Corporate debt securities
U.S. government and federal agency securities
Municipal securities
Sovereign obligations
Loans
Derivatives	(2,747,077)	(2,352,611)
Physical commodities
Total financial instruments sold, not yet purchased	(2,747,077)	(2,352,611)
Obligation to return securities received as collateral
Other secured financings
Embedded conversion option
Counterparty and Cash Collateral Netting [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets
Financial instruments sold, not yet purchased:
Mortgage- and asset-backed securities, liabilities
Counterparty and Cash Collateral Netting [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets
Counterparty and Cash Collateral Netting [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets