Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	May. 31, 2015	Nov. 30, 2014
Financial instruments owned:
Corporate equity securities	$ 2,846,831	$ 2,426,242
Corporate debt securities	3,425,443	3,365,042
Collateralized debt obligations	255,821	430,868
U.S. government and federal agency securities	2,922,875	2,775,541
Municipal securities	638,604	590,849
Sovereign obligations	2,497,735	2,759,511
Loans and other receivables	1,708,575	1,556,018
Derivatives	402,089	406,268
Investments at fair value	132,061	126,372
Physical commodities	45,191	62,234
Total financial instruments owned, excluding Investments at fair value based on NAV	18,800,715	18,594,443
Counterparty and Cash Collateral Netting	(4,106,430)	(4,759,345)
Cash and cash equivalents	3,288,758	4,079,968
Cash and securities segregated and on deposit for regulatory purposes	2,396,114	3,444,674
Securities received as collateral	9,623	5,418
Financial instruments sold, not yet purchased:
Corporate equity securities	2,191,220	1,985,864
Corporate debt securities	1,569,882	1,612,217
Collateralized debt obligations		4,557
U.S. government and federal agency securities	2,090,062	2,253,055
Sovereign obligations	2,076,967	1,791,085
Loans	968,329	870,975
Derivatives	250,722	363,515
Total financial instruments sold, not yet purchased	9,195,450	8,881,268
Counterparty and Cash Collateral Netting	(4,205,980)	(4,856,618)
Obligation to return securities received as collateral	9,623	5,418
Other secured financings	56,060	30,825
Embedded conversion option	725	693
Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	2,898,231	2,962,511
Financial instruments sold, not yet purchased:
Residential mortgage-backed securities	48,268
Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	926,671	993,306
Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	100,588	139,681
Level 1 [Member]
Financial instruments owned:
Corporate equity securities	2,639,204	2,178,837
Corporate debt securities	0	0
Collateralized debt obligations	0	0
U.S. government and federal agency securities	2,615,590	2,694,268
Municipal securities	0	0
Sovereign obligations	1,256,242	1,968,747
Loans and other receivables	0	0
Derivatives	64,371	65,145
Investments at fair value	0	0
Physical commodities	0	0
Total financial instruments owned, excluding Investments at fair value based on NAV	6,575,407	6,906,997
Cash and cash equivalents	3,288,758	4,079,968
Cash and securities segregated and on deposit for regulatory purposes	2,396,114	3,444,674
Securities received as collateral	9,623	5,418
Financial instruments sold, not yet purchased:
Corporate equity securities	2,134,344	1,911,145
Corporate debt securities	0	0
Collateralized debt obligations		0
U.S. government and federal agency securities	1,955,173	2,253,055
Sovereign obligations	1,228,416	1,217,075
Loans	0	0
Derivatives	38,035	52,778
Total financial instruments sold, not yet purchased	5,355,968	5,434,053
Obligation to return securities received as collateral	9,623	5,418
Other secured financings	0	0
Embedded conversion option	0	0
Level 1 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	0	0
Financial instruments sold, not yet purchased:
Residential mortgage-backed securities	0
Level 1 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	0	0
Level 1 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	0	0
Level 2 [Member]
Financial instruments owned:
Corporate equity securities	187,080	226,441
Corporate debt securities	3,393,526	3,342,276
Collateralized debt obligations	166,814	306,218
U.S. government and federal agency securities	307,285	81,273
Municipal securities	638,604	590,849
Sovereign obligations	1,241,493	790,764
Loans and other receivables	1,599,819	1,458,760
Derivatives	4,404,136	5,046,278
Investments at fair value	718	73,148
Physical commodities	45,191	62,234
Total financial instruments owned, excluding Investments at fair value based on NAV	15,791,742	15,962,233
Cash and cash equivalents	0	0
Cash and securities segregated and on deposit for regulatory purposes	0	0
Securities received as collateral	0	0
Financial instruments sold, not yet purchased:
Corporate equity securities	56,838	74,681
Corporate debt securities	1,569,430	1,611,994
Collateralized debt obligations		4,557
U.S. government and federal agency securities	134,889	0
Sovereign obligations	848,551	574,010
Loans	957,597	856,525
Derivatives	4,380,241	5,117,803
Total financial instruments sold, not yet purchased	7,995,814	8,239,570
Obligation to return securities received as collateral	0	0
Other secured financings	0	0
Embedded conversion option	0	0
Level 2 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	2,809,536	2,879,954
Financial instruments sold, not yet purchased:
Residential mortgage-backed securities	48,268
Level 2 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	908,809	966,651
Level 2 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	88,731	137,387
Level 3 [Member]
Financial instruments owned:
Corporate equity securities	20,547	20,964
Corporate debt securities	31,917	22,766
Collateralized debt obligations	89,007	124,650
U.S. government and federal agency securities	0	0
Municipal securities	0	0
Sovereign obligations	0	0
Loans and other receivables	108,756	97,258
Derivatives	40,012	54,190
Investments at fair value	131,343	53,224
Physical commodities	0	0
Total financial instruments owned, excluding Investments at fair value based on NAV	539,996	484,558
Cash and cash equivalents	0	0
Cash and securities segregated and on deposit for regulatory purposes	0	0
Securities received as collateral	0	0
Financial instruments sold, not yet purchased:
Corporate equity securities	38	38
Corporate debt securities	452	223
Collateralized debt obligations		0
U.S. government and federal agency securities	0	0
Sovereign obligations	0	0
Loans	10,732	14,450
Derivatives	38,426	49,552
Total financial instruments sold, not yet purchased	49,648	64,263
Obligation to return securities received as collateral	0	0
Other secured financings	56,060	30,825
Embedded conversion option	725	693
Level 3 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	88,695	82,557
Financial instruments sold, not yet purchased:
Residential mortgage-backed securities	0
Level 3 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	17,862	26,655
Level 3 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	$ 11,857	$ 2,294