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		6 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Assets:
Total gains/(losses) (realized and unrealized)	$ (2,700)	$ (21,400)	$ (12,000)	$ (51,900)
Liabilities:
Total gains/(losses) (realized and unrealized)	(300)	(300)	2,400	(9,500)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	324	38	313	38
Total gains/(losses) (realized and unrealized)	30	0	41	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	0	(38)	0	(38)
Ending Balance	354	0	354	0
Change in unrealized gains/ (losses) relating to instruments still held	(30)	0	(41)	0
Corporate debt securities [Member]
Liabilities:
Beginning Balance	523		523
Total gains/(losses) (realized and unrealized)	(1)		(1)
Purchases	0		0
Sales	0		0
Settlements	0		0
Issuances	0		0
Net transfers into/ (out of) Level 3	0		0
Ending Balance	522		522
Change in unrealized gains/ (losses) relating to instruments still held	1		1
CMBS [Member]
Liabilities:
Beginning Balance	0		0
Total gains/(losses) (realized and unrealized)	70		70
Purchases	0		0
Sales	0		0
Settlements	0		0
Issuances	0		0
Net transfers into/ (out of) Level 3	0		0
Ending Balance	70		70
Change in unrealized gains/ (losses) relating to instruments still held	(70)		(70)
Net derivatives [Member]
Liabilities:
Beginning Balance	6,413	11,757	3,441	(242)
Total gains/(losses) (realized and unrealized)	(3,617)	3	(6,154)	10,075
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(3)	(83)	1,534	(46)
Issuances	218	451	404	1,005
Net transfers into/ (out of) Level 3	11	(7,704)	3,797	(6,368)
Ending Balance	3,022	4,424	3,022	4,424
Change in unrealized gains/ (losses) relating to instruments still held	(147)	(3)	(614)	(11,008)
Loans [Member]
Liabilities:
Beginning Balance	1,036	7,744	378	10,469
Total gains/(losses) (realized and unrealized)	3,867	(261)	4,091	(541)
Purchases	0	0	(364)	(2,240)
Sales	0	0	0	1,033
Settlements	0	(71)	0	(1,149)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	64	(5,516)	862	(5,676)
Ending Balance	4,967	1,896	4,967	1,896
Change in unrealized gains/ (losses) relating to instruments still held	(3,867)	261	(4,091)	250
Other secured financings [Member]
Liabilities:
Beginning Balance	87	538	418	544
Total gains/(losses) (realized and unrealized)	(87)	(70)	(418)	(76)
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	0	0	0	0
Ending Balance	0	468	0	468
Change in unrealized gains/ (losses) relating to instruments still held	0	70	0	76
Corporate equity securities [Member]
Assets:
Beginning Balance	20,580	30,540	21,739	40,906
Total gains/(losses) (realized and unrealized)	(1,198)	(927)	(489)	1,571
Purchases	490	200	1,056	2,287
Sales	(1,263)	(508)	(1,117)	(508)
Settlements	(281)	(2,455)	(1,907)	(2,455)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	2,220	21,966	1,266	7,015
Ending Balance	20,548	48,816	20,548	48,816
Change in unrealized gains/(losses) relating to instruments still held	(1,428)	(849)	(1,215)	2,080
Corporate debt securities [Member]
Assets:
Beginning Balance	33,467	25,634	25,005	25,876
Total gains/(losses) (realized and unrealized)	(1,420)	474	(3,300)	(2,378)
Purchases	8,789	15	15,133	16,564
Sales	(9,181)	(789)	(15,295)	(16,613)
Settlements	(6,986)	0	(1,693)	(245)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	58	(1,221)	4,877	909
Ending Balance	24,727	24,113	24,727	24,113
Change in unrealized gains/(losses) relating to instruments still held	(1,983)	347	(3,571)	(2,474)
CDOs and CLOs [Member]
Assets:
Beginning Balance	45,354	67,348	54,354	85,092
Total gains/(losses) (realized and unrealized)	(2,721)	1,797	(10,102)	(20,455)
Purchases	16,334	943	24,741	24,024
Sales	(33,546)	(21,233)	(44,725)	(43,696)
Settlements	0	0	0	(473)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	1,834	3,855	2,987	8,218
Ending Balance	27,255	52,710	27,255	52,710
Change in unrealized gains/(losses) relating to instruments still held	(131)	2,534	(204)	(12,002)
Sovereign obligations [Member]
Assets:
Beginning Balance		119		120
Total gains/(losses) (realized and unrealized)		1		0
Purchases		0		0
Sales		0		0
Settlements		0		0
Issuances		0		0
Net transfers into/ (out of) Level 3		0		0
Ending Balance		120		120
Change in unrealized gains/(losses) relating to instruments still held		1		0
Municipal securities [Member]
Assets:
Beginning Balance	26,554		27,257
Total gains/(losses) (realized and unrealized)	(70)		(1,547)
Purchases	0		0
Sales	(26,484)		(25,710)
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	39,259	68,019	38,772	70,263
Total gains/(losses) (realized and unrealized)	(2,188)	(4,915)	(3,000)	(8,337)
Purchases	3,176	3,422	5,886	1,483
Sales	(6,636)	(2,837)	(11,750)	(4,843)
Settlements	(4)	(122)	(16)	(235)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(575)	(259)	3,140	4,977
Ending Balance	33,032	63,308	33,032	63,308
Change in unrealized gains/(losses) relating to instruments still held	(1,024)	(2,233)	(1,667)	(4,011)
CMBS [Member]
Assets:
Beginning Balance	20,653	21,994	20,580	14,326
Total gains/(losses) (realized and unrealized)	98	(1,140)	(1,119)	(2,589)
Purchases	534	0	534	2,951
Sales	(4,111)	0	(4,523)	(2,023)
Settlements	(1)	(311)	(2)	(1,208)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(910)	4,440	793	13,526
Ending Balance	16,263	24,983	16,263	24,983
Change in unrealized gains/(losses) relating to instruments still held	(546)	(1,306)	(907)	(3,140)
Other ABS [Member]
Assets:
Beginning Balance	37,702	33,124	40,911	42,925
Total gains/(losses) (realized and unrealized)	(3,663)	(7,284)	(5,489)	(202)
Purchases	13,476	3,549	17,029	64,833
Sales	0	(1,068)	(300)	(74,690)
Settlements	(2,241)	(52)	(5,576)	(4,713)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(1,925)	14,764	(3,226)	14,880
Ending Balance	43,349	43,033	43,349	43,033
Change in unrealized gains/(losses) relating to instruments still held	(3,642)	(7,275)	(5,461)	(7,134)
Loans and other receivables [Member]
Assets:
Beginning Balance	53,172	155,442	81,872	189,289
Total gains/(losses) (realized and unrealized)	3,226	(7,792)	10,062	(13,376)
Purchases	20,054	20,836	63,616	203,990
Sales	(19,378)	(13,347)	(61,423)	(127,944)
Settlements	(7,181)	(55,541)	(17,017)	(150,975)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(528)	4,801	(27,745)	3,415
Ending Balance	49,365	104,399	49,365	104,399
Change in unrealized gains/(losses) relating to instruments still held	1,687	(6,231)	3,679	(15,693)
Investments at fair value [Member]
Assets:
Beginning Balance	83,785	63,582	96,369	53,120
Total gains/(losses) (realized and unrealized)	5,194	(1,574)	2,995	(6,090)
Purchases	300	40	300	1,227
Sales	0	0	(10,119)	0
Settlements	(273)	(283)	(539)	(555)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	(4,000)	0	10,063
Ending Balance	89,006	57,765	89,006	57,765
Change in unrealized gains/(losses) relating to instruments still held	$ 5,194	$ (6)	$ 5,019	$ 911