Fair Value Disclosures - Summary of Changes in Fair Value of Financial Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2016	Aug. 31, 2015
Assets:
Total gains/(losses) (realized and unrealized)	$ (48,300)	$ 64,900	$ (93,100)	$ 48,500
Liabilities:
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	5,400	1,700	(2,800)	(2,300)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	0	38	38	38
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	38	(38)	0	(38)
Ending Balance	38	0	38	0
Change in unrealized gains/ (losses) relating to instruments still held	0	0	0	0
Corporate debt securities [Member]
Liabilities:
Beginning Balance	0	452	0	223
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(27)	(226)	(27)	(1)
Purchases	0	0	0	(6,677)
Sales	550	0	550	6,804
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	0	0	(123)
Ending Balance	523	226	523	226
Change in unrealized gains/ (losses) relating to instruments still held	(27)	226	0	(226)
Net derivatives [Member]
Liabilities:
Beginning Balance	4,424	(1,586)	(242)	(4,638)
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(4,736)	(1,020)	3,104	3,022
Purchases	0	(1,432)	0	(4,527)
Sales	11,101	11,618	11,101	11,340
Settlements	32	24	(14)	(30)
Issuances	601	416	1,606	1,901
Net transfers into/ (out of) Level 3	(375)	(857)	(4,508)	95
Ending Balance	11,047	7,163	11,047	7,163
Change in unrealized gains/ (losses) relating to instruments still held	(1,589)	551	(5,745)	(5,211)
Loans [Member]
Liabilities:
Beginning Balance	1,896	10,732	10,469	14,450
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(402)	109	7	(102)
Purchases	0	(3,012)	0	(3,487)
Sales	170	0	681	0
Settlements	0	0	(213)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(816)	2,542	(10,096)	(490)
Ending Balance	848	10,371	848	10,371
Change in unrealized gains/ (losses) relating to instruments still held	(400)	(110)	45	102
Other secured financings [Member]
Liabilities:
Beginning Balance	468	56,060	544	30,825
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(200)	0	(276)	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	(3,914)	0	(15,674)
Issuances	0	0	0	36,995
Net transfers into/ (out of) Level 3	0	(51,572)	0	(51,572)
Ending Balance	268	574	268	574
Change in unrealized gains/ (losses) relating to instruments still held	200	0	276	0
Embedded conversion option [Member]
Liabilities:
Beginning Balance		725		693
Net gains/(losses) on Level 3 liabilities (realized and unrealized)		(611)		(579)
Purchases		0		0
Sales		0		0
Settlements		0		0
Issuances		0		0
Net transfers into/ (out of) Level 3		0		0
Ending Balance		114		114
Change in unrealized gains/ (losses) relating to instruments still held		611		579
Corporate equity securities [Member]
Assets:
Beginning Balance	48,816	20,547	40,906	20,964
Total gains/(losses) (realized and unrealized)	(6,492)	3,901	(8,388)	10,247
Purchases	291	21,162	5,225	22,631
Sales	(49)	(5,173)	(49)	(5,176)
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(20,371)	(1,935)	(15,499)	(10,164)
Ending Balance	22,195	38,502	22,195	38,502
Change in unrealized gains/(losses) relating to instruments still held	(892)	3,803	(727)	10,210
Corporate debt securities [Member]
Assets:
Beginning Balance	24,113	31,917	25,876	22,766
Total gains/(losses) (realized and unrealized)	(145)	(5,276)	5,239	(5,425)
Purchases	10,696	10,395	29,629	83,613
Sales	(5,046)	(17,197)	(20,331)	(88,711)
Settlements	0	(1)	0	(1)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	5,389	4,493	(5,406)	12,089
Ending Balance	35,007	24,331	35,007	24,331
Change in unrealized gains/(losses) relating to instruments still held	405	(5,544)	1,456	(5,797)
CDOs and CLOs [Member]
Assets:
Beginning Balance	52,710	89,007	85,092	124,650
Total gains/(losses) (realized and unrealized)	(4,067)	(12,560)	(24,356)	(28,999)
Purchases	4,205	14,961	61,707	63,038
Sales	(5,203)	0	(69,397)	(47,570)
Settlements	0	(13,230)	(605)	(20,481)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(3,575)	2,872	(8,371)	(9,588)
Ending Balance	44,070	81,050	44,070	81,050
Change in unrealized gains/(losses) relating to instruments still held	(4,606)	(12,561)	(13,196)	(22,654)
Municipal securities [Member]
Assets:
Beginning Balance	0		0
Total gains/(losses) (realized and unrealized)	(7,074)		(1,462)
Purchases	0		0
Sales	0		0
Settlements	0		0
Issuances	0		0
Net transfers into/ (out of) Level 3	34,331		28,719
Ending Balance	27,257		27,257
Change in unrealized gains/(losses) relating to instruments still held	(7,074)		(1,462)
Sovereign obligations [Member]
Assets:
Beginning Balance	120		120
Total gains/(losses) (realized and unrealized)	5		5
Purchases	0		0
Sales	(125)		(125)
Settlements	0		0
Issuances	0		0
Net transfers into/ (out of) Level 3	0		0
Ending Balance	0		0
Change in unrealized gains/(losses) relating to instruments still held	0		0
RMBS [Member]
Assets:
Beginning Balance	63,308	88,695	70,263	82,557
Total gains/(losses) (realized and unrealized)	(2,343)	(3,009)	(7,243)	(6,776)
Purchases	1,884	10,034	1,948	30,865
Sales	(10,874)	(8,424)	(13,203)	(25,222)
Settlements	(463)	(195)	(1,078)	(358)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(4,631)	(679)	(3,806)	5,356
Ending Balance	46,881	86,422	46,881	86,422
Change in unrealized gains/(losses) relating to instruments still held	(183)	655	228	(2,507)
Commercial mortgage-backed securities [Member]
Assets:
Beginning Balance	24,983	17,862	14,326	26,655
Total gains/(losses) (realized and unrealized)	(1,531)	(510)	(4,606)	(2,053)
Purchases	0	0	1,256	3,366
Sales	0	(680)	(2,023)	(9,973)
Settlements	0	0	0	(6,981)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	1,141	(1,525)	15,640	4,133
Ending Balance	24,593	15,147	24,593	15,147
Change in unrealized gains/(losses) relating to instruments still held	(236)	(545)	(3,337)	(1,851)
Other asset-backed securities [Member]
Assets:
Beginning Balance	43,033	11,857	42,925	2,294
Total gains/(losses) (realized and unrealized)	(2,247)	870	(2,420)	666
Purchases	3,416	21,913	66,503	69,892
Sales	(2,727)	0	(60,525)	(40,000)
Settlements	(1,429)	(1,167)	(6,678)	(1,438)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	21,066	(877)	21,307	1,182
Ending Balance	61,112	32,596	61,112	32,596
Change in unrealized gains/(losses) relating to instruments still held	(2,202)	813	(9,993)	607
Loans and other receivables [Member]
Assets:
Beginning Balance	104,399	108,756	189,289	97,258
Total gains/(losses) (realized and unrealized)	(23,445)	(2,111)	(30,843)	(7,331)
Purchases	31,512	31,269	305,920	115,370
Sales	(10,140)	(603)	(206,587)	(40,978)
Settlements	(16,804)	(42,529)	(163,913)	(82,100)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(7,065)	617	(15,409)	13,180
Ending Balance	78,457	95,399	78,457	95,399
Change in unrealized gains/(losses) relating to instruments still held	(16,044)	(6,182)	(27,714)	(8,850)
Investments at fair value [Member]
Assets:
Beginning Balance	57,765	131,343	53,120	53,224
Total gains/(losses) (realized and unrealized)	(966)	83,580	(19,055)	88,195
Purchases	0	0	26,227	0
Sales	(485)	(127,427)	(485)	(124,854)
Settlements	(278)	(277)	(834)	(3,818)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	29,000	(21,010)	26,063	53,462
Ending Balance	85,036	66,209	85,036	66,209
Change in unrealized gains/(losses) relating to instruments still held	$ (1,113)	$ 19,675	$ (11,988)	$ 24,372