Fair Value Disclosures - Financial Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Aug. 31, 2015	Nov. 30, 2014
Financial instruments owned:
Corporate equity securities	$ 2,669,812	$ 2,426,242
Corporate debt securities	2,980,521	3,365,042
Collateralized debt obligations	232,549	430,868
U.S. government and federal agency securities	2,701,407	2,775,541
Municipal securities	599,471	590,849
Sovereign obligations	1,851,326	2,759,511
Loans and other receivables	1,761,853	1,556,018
Derivatives	468,823	406,268
Investments at fair value	83,075	126,372
Physical commodities	14,973	62,234
Total financial instruments owned, excluding Investments at fair value based on NAV	18,852,127	18,594,443
Counterparty and Cash Collateral Netting	(4,394,947)	(4,759,345)
Cash and cash equivalents	3,441,785	4,079,968
Cash and securities segregated and on deposit for regulatory purposes	904,009	3,444,674
Securities received as collateral	11,365	5,418
Financial instruments sold, not yet purchased:
Corporate equity securities	1,810,989	1,985,864
Corporate debt securities	1,932,760	1,612,217
Collateralized debt obligations		4,557
U.S. government and federal agency securities	2,547,621	2,253,055
Sovereign obligations	2,103,082	1,791,085
Loans	830,212	870,975
Derivatives	219,643	363,515
Total financial instruments sold, not yet purchased	9,447,636	8,881,268
Counterparty and Cash Collateral Netting	(4,504,522)	(4,856,618)
Obligation to return securities received as collateral	11,365	5,418
Other secured financings	70,901	30,825
Embedded conversion option	114	693
Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	3,910,811	2,962,511
Financial instruments sold, not yet purchased:
Residential mortgage-backed securities	3,329
Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	1,480,262	993,306
Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	97,244	139,681
Level 1 [Member]
Financial instruments owned:
Corporate equity securities	2,454,674	2,178,837
Corporate debt securities	0	0
Collateralized debt obligations	0	0
U.S. government and federal agency securities	2,109,086	2,694,268
Municipal securities	0	0
Sovereign obligations	1,052,681	1,968,747
Loans and other receivables	0	0
Derivatives	2,182	65,145
Investments at fair value	0	0
Physical commodities	0	0
Total financial instruments owned, excluding Investments at fair value based on NAV	5,618,623	6,906,997
Cash and cash equivalents	3,441,785	4,079,968
Cash and securities segregated and on deposit for regulatory purposes	904,009	3,444,674
Securities received as collateral	11,365	5,418
Financial instruments sold, not yet purchased:
Corporate equity securities	1,711,938	1,911,145
Corporate debt securities	0	0
Collateralized debt obligations		0
U.S. government and federal agency securities	2,414,440	2,253,055
Sovereign obligations	1,228,377	1,217,075
Loans	0	0
Derivatives	1,931	52,778
Total financial instruments sold, not yet purchased	5,356,686	5,434,053
Obligation to return securities received as collateral	11,365	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	176,636	226,441
Corporate debt securities	2,956,190	3,342,276
Collateralized debt obligations	151,499	306,218
U.S. government and federal agency securities	592,321	81,273
Municipal securities	599,471	590,849
Sovereign obligations	798,645	790,764
Loans and other receivables	1,666,454	1,458,760
Derivatives	4,827,243	5,046,278
Investments at fair value	16,866	73,148
Physical commodities	14,973	62,234
Total financial instruments owned, excluding Investments at fair value based on NAV	17,154,450	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	99,051	74,681
Corporate debt securities	1,932,534	1,611,994
Collateralized debt obligations		4,557
U.S. government and federal agency securities	133,181	0
Sovereign obligations	874,705	574,010
Loans	819,841	856,525
Derivatives	4,680,726	5,117,803
Total financial instruments sold, not yet purchased	8,543,367	8,239,570
Obligation to return securities received as collateral	0	0
Other secured financings	70,327	0
Embedded conversion option	0	0
Level 2 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	3,824,389	2,879,954
Financial instruments sold, not yet purchased:
Residential mortgage-backed securities	3,329
Level 2 [Member] | Commercial mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	1,465,115	966,651
Level 2 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	64,648	137,387
Level 3 [Member]
Financial instruments owned:
Corporate equity securities	38,502	20,964
Corporate debt securities	24,331	22,766
Collateralized debt obligations	81,050	124,650
U.S. government and federal agency securities	0	0
Municipal securities	0	0
Sovereign obligations	0	0
Loans and other receivables	95,399	97,258
Derivatives	34,345	54,190
Investments at fair value	66,209	53,224
Physical commodities	0	0
Total financial instruments owned, excluding Investments at fair value based on NAV	474,001	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	0	38
Corporate debt securities	226	223
Collateralized debt obligations		0
U.S. government and federal agency securities	0	0
Sovereign obligations	0	0
Loans	10,371	14,450
Derivatives	41,508	49,552
Total financial instruments sold, not yet purchased	52,105	64,263
Obligation to return securities received as collateral	0	0
Other secured financings	574	30,825
Embedded conversion option	114	693
Level 3 [Member] | Residential mortgage-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	86,422	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	15,147	26,655
Level 3 [Member] | Other asset-backed securities [Member]
Financial instruments owned:
Mortgage- and asset-backed securities, assets	$ 32,596	$ 2,294