Fair Value Disclosures - Summary of Changes in Fair Value of Financial Assets Classified as Level 3 (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Feb. 28, 2013		Feb. 29, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total gains/losses (realized and unrealized)	$ (14,500)		$ 9,700
Corporate equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	16,815		13,489
Total gains/losses (realized and unrealized)	200	[1]	1,684	[1]
Purchases	707		14,184
Sales	109
Net transfers into/ (out of) Level 3	(4,597)		912
Ending Balance	13,234		30,269
Change in unrealized gains/(losses) relating to instruments still held	172	[1]	1,685	[1]
Corporate debt securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	3,631		48,140
Total gains/losses (realized and unrealized)	7,836	[1]	671	[1]
Purchases	11,510		271
Sales	(1,918)		(22,300)
Settlements			(1,276)
Net transfers into/ (out of) Level 3	10,761		8,100
Ending Balance	31,820		33,606
Change in unrealized gains/(losses) relating to instruments still held	7,833	[1]	(737)	[1]
Collateralized debt obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	31,255		47,988
Total gains/losses (realized and unrealized)	3,624	[1]	(796)	[1]
Purchases	9,406
Sales	(17,374)		(14,063)
Settlements			(3,328)
Net transfers into/ (out of) Level 3	2,865		42,775
Ending Balance	29,776		72,576
Change in unrealized gains/(losses) relating to instruments still held	(1,125)	[1]	(1,488)	[1]
Municipal securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			6,904
Total gains/losses (realized and unrealized)			(71)	[1]
Sales			(740)
Net transfers into/ (out of) Level 3			(4,917)
Ending Balance			1,176
Change in unrealized gains/(losses) relating to instruments still held			12	[1]
Sovereign obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			140
Total gains/losses (realized and unrealized)				[1]
Purchases
Sales
Settlements
Net transfers into/ (out of) Level 3
Ending Balance			140
Change in unrealized gains/(losses) relating to instruments still held				[1]
Residential mortgage-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	156,069		149,965
Total gains/losses (realized and unrealized)	11,906	[1]	(6,492)	[1]
Purchases	132,773		10,497
Sales	(130,143)		(44,282)
Settlements	(6,057)		(6,881)
Net transfers into/ (out of) Level 3	4,878		25,944
Ending Balance	169,426		128,751
Change in unrealized gains/(losses) relating to instruments still held	4,511	[1]	(5,995)	[1]
Commercial mortgage-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	30,202		52,407
Total gains/losses (realized and unrealized)	(995)	[1]	(1,655)	[1]
Purchases	2,280
Sales	(2,866)		(3,593)
Settlements	(1,188)		(44)
Net transfers into/ (out of) Level 3	(9,639)		(11,323)
Ending Balance	17,794		35,792
Change in unrealized gains/(losses) relating to instruments still held	(2,059)	[1]	(1,419)	[1]
Other asset-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,114		3,284
Total gains/losses (realized and unrealized)	50	[1]	(104)	[1]
Purchases	1,627
Sales	(1,342)		(197)
Settlements	(19)		(40)
Net transfers into/ (out of) Level 3	(178)		2,446
Ending Balance	1,252		5,389
Change in unrealized gains/(losses) relating to instruments still held	(1)	[1]	(76)	[1]
Loans and other receivables [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	180,393		97,291
Total gains/losses (realized and unrealized)	(8,682)	[1]	1,899	[1]
Purchases	105,650		48,309
Sales	(29,828)		(21,733)
Settlements	(61,407)		(25,729)
Net transfers into/ (out of) Level 3	(15,140)		4,412
Ending Balance	170,986		104,449
Change in unrealized gains/(losses) relating to instruments still held	(12,374)	[1]	643	[1]
Investments at fair value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	83,897		78,326
Total gains/losses (realized and unrealized)	961	[1]	1,378	[1]
Purchases	952		480
Sales	(4,923)		(1,797)
Settlements	(9,721)		(277)
Net transfers into/ (out of) Level 3	(1,099)
Ending Balance	70,067		78,110
Change in unrealized gains/(losses) relating to instruments still held	1,171	[1]	1,378	[1]
Investments in managed funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	57,763		70,740
Total gains/losses (realized and unrealized)	(363)	[1]	(6,212)	[1]
Purchases	11,068		8,499
Sales			(12)
Settlements	(8,492)
Ending Balance	59,976		73,015
Change in unrealized gains/(losses) relating to instruments still held	$ (363)	[1]	$ (6,212)	[1]

[1] Realized and unrealized gains/losses are reported in Principal transactions in the Consolidated Statements of Earnings.