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, 2017	Aug. 31, 2016	Aug. 31, 2017	Aug. 31, 2016
Assets:
Total gains/(losses) (realized and unrealized)	$ 6,000	$ (48,300)	$ (900)	$ (93,100)
Liabilities:
Total gains/(losses) (realized and unrealized)	6,000	5,400	1,500	(2,800)
Corporate equity securities
Liabilities:
Beginning Balance	354	0	313	38
Total gains/(losses) (realized and unrealized)	107	0	134	0
Purchases	(369)	0	(355)	0
Sales	27	0	27	0
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	38	0	0
Ending Balance	119	38	119	38
Change in unrealized gains/ (losses) relating to instruments still held	(92)	0	(92)	0
Corporate debt securities
Liabilities:
Beginning Balance	522	0	523	0
Total gains/(losses) (realized and unrealized)	0	(27)	(1)	(27)
Purchases	0	0	0	0
Sales	0	550	0	550
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	0	0	0
Ending Balance	522	523	522	523
Change in unrealized gains/ (losses) relating to instruments still held	0	(27)	1	0
CMBS
Liabilities:
Beginning Balance	70		0
Total gains/(losses) (realized and unrealized)	(35)		35
Purchases	0		0
Sales	0		0
Settlements	0		0
Issuances	0		0
Net transfers into/ (out of) Level 3	0		0
Ending Balance	35		35
Change in unrealized gains/ (losses) relating to instruments still held	(35)		(35)
Net derivatives
Liabilities:
Beginning Balance	3,022	4,424	3,441	(242)
Total gains/(losses) (realized and unrealized)	(2,980)	(4,736)	(2,854)	3,104
Purchases	0	0	0	0
Sales	0	11,101	0	11,101
Settlements	5,040	32	5,162	(14)
Issuances	0	601	404	1,606
Net transfers into/ (out of) Level 3	0	(375)	(1,071)	(4,508)
Ending Balance	5,082	11,047	5,082	11,047
Change in unrealized gains/ (losses) relating to instruments still held	(2,474)	(1,589)	(2,333)	(5,745)
Loans
Liabilities:
Beginning Balance	4,967	1,896	378	10,469
Total gains/(losses) (realized and unrealized)	(3,071)	(402)	1,604	7
Purchases	0	0	(364)	0
Sales	333	170	333	681
Settlements	0	0	0	(213)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	1,056	(816)	1,334	(10,096)
Ending Balance	3,285	848	3,285	848
Change in unrealized gains/ (losses) relating to instruments still held	3,018	(400)	(1,583)	45
Other secured financings
Liabilities:
Beginning Balance		468	418	544
Total gains/(losses) (realized and unrealized)		(200)	(418)	(276)
Purchases		0	0	0
Sales		0	0	0
Settlements		0	0	0
Issuances		0	0	0
Net transfers into/ (out of) Level 3		0	0	0
Ending Balance	0	268	0	268
Change in unrealized gains/ (losses) relating to instruments still held		200	0	276
Corporate equity securities
Assets:
Beginning Balance	20,548	48,816	21,739	40,906
Total gains/(losses) (realized and unrealized)	4,344	(6,492)	3,416	(8,388)
Purchases	4	291	945	5,225
Sales	(645)	(49)	(1,502)	(49)
Settlements	(55)	0	(356)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(2,022)	(20,371)	(2,068)	(15,499)
Ending Balance	22,174	22,195	22,174	22,195
Change in unrealized gains/(losses) relating to instruments still held	4,319	(892)	2,689	(727)
Corporate debt securities
Assets:
Beginning Balance	24,727	24,113	25,005	25,876
Total gains/(losses) (realized and unrealized)	(2,350)	(145)	(3,280)	5,239
Purchases	5,901	10,696	19,610	29,629
Sales	(5,551)	(5,046)	(18,364)	(20,331)
Settlements	(31)	0	(1,724)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	2,319	5,389	3,768	(5,406)
Ending Balance	25,015	35,007	25,015	35,007
Change in unrealized gains/(losses) relating to instruments still held	(2,224)	405	(3,424)	1,456
CDOs and CLOs
Assets:
Beginning Balance	27,255	52,710	54,354	85,092
Total gains/(losses) (realized and unrealized)	(6,119)	(4,067)	(13,902)	(24,356)
Purchases	52,918	4,205	65,523	61,707
Sales	(36,564)	(5,203)	(72,122)	(69,397)
Settlements	245	0	239	(605)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	468	(3,575)	4,111	(8,371)
Ending Balance	38,203	44,070	38,203	44,070
Change in unrealized gains/(losses) relating to instruments still held	(3,552)	(4,606)	(3,685)	(13,196)
Sovereign obligations
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
Municipal securities
Assets:
Beginning Balance		0	27,257	0
Total gains/(losses) (realized and unrealized)		(7,074)	(1,547)	(1,462)
Purchases		0	0	0
Sales		0	(25,710)	0
Settlements		0	0	0
Issuances		0	0	0
Net transfers into/ (out of) Level 3		34,331	0	28,719
Ending Balance	0	27,257	0	27,257
Change in unrealized gains/(losses) relating to instruments still held		(7,074)	0	(1,462)
RMBS
Assets:
Beginning Balance	33,032	63,308	38,772	70,263
Total gains/(losses) (realized and unrealized)	(263)	(2,343)	(1,446)	(7,243)
Purchases	494	1,884	113,391	1,948
Sales	(732)	(10,874)	(125,731)	(13,203)
Settlements	(291)	(463)	(572)	(1,078)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(11,591)	(4,631)	(3,765)	(3,806)
Ending Balance	20,649	46,881	20,649	46,881
Change in unrealized gains/(losses) relating to instruments still held	188	(183)	(2,005)	228
CMBS
Assets:
Beginning Balance	16,263	24,983	20,580	14,326
Total gains/(losses) (realized and unrealized)	(125)	(1,531)	(1,180)	(4,606)
Purchases	0	0	2,033	1,256
Sales	(676)	0	(5,199)	(2,023)
Settlements	(637)	0	(985)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	2,811	1,141	2,387	15,640
Ending Balance	17,636	24,593	17,636	24,593
Change in unrealized gains/(losses) relating to instruments still held	(161)	(236)	(952)	(3,337)
Other ABS
Assets:
Beginning Balance	43,349	43,033	40,911	42,925
Total gains/(losses) (realized and unrealized)	(6,454)	(2,247)	(15,338)	(2,420)
Purchases	5,798	3,416	67,611	66,503
Sales	(3,789)	(2,727)	(4,121)	(60,525)
Settlements	(2,924)	(1,429)	(16,891)	(6,678)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	32,966	21,066	(3,226)	21,307
Ending Balance	68,946	61,112	68,946	61,112
Change in unrealized gains/(losses) relating to instruments still held	(3,570)	(2,202)	(8,872)	(9,993)
Loans and other receivables
Assets:
Beginning Balance	49,365	104,399	81,872	189,289
Total gains/(losses) (realized and unrealized)	15,261	(23,445)	27,709	(30,843)
Purchases	9,265	31,512	84,342	305,920
Sales	(5,854)	(10,140)	(83,791)	(206,587)
Settlements	(8,249)	(16,804)	(23,241)	(163,913)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	2,868	(7,065)	(24,235)	(15,409)
Ending Balance	62,656	78,457	62,656	78,457
Change in unrealized gains/(losses) relating to instruments still held	14,005	(16,044)	16,294	(27,714)
Investments at fair value
Assets:
Beginning Balance	89,006	57,765	96,369	53,120
Total gains/(losses) (realized and unrealized)	1,703	(966)	4,698	(19,055)
Purchases	0	0	300	26,227
Sales	0	(485)	(10,119)	(485)
Settlements	(292)	(278)	(831)	(834)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	29,000	0	26,063
Ending Balance	90,417	85,036	90,417	85,036
Change in unrealized gains/(losses) relating to instruments still held	$ 1,703	$ (1,113)	$ 6,721	$ (11,988)