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
	Feb. 28, 2017	Feb. 29, 2016
Assets:
Total gains/(losses) (realized and unrealized)	$ (10,200)	$ (42,200)
Liabilities:
Total gains/(losses) (realized and unrealized)	4,200	(10,000)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	313	38
Total gains/(losses) (realized and unrealized)	11	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	0
Ending Balance	324	38
Change in unrealized gains/ (losses) relating to instruments still held	(11)	0
Corporate debt securities [Member]
Liabilities:
Beginning Balance	523
Total gains/(losses) (realized and unrealized)	0
Purchases	0
Sales	0
Settlements	0
Issuances	0
Net transfers into/ (out of) Level 3	0
Ending Balance	523
Change in unrealized gains/ (losses) relating to instruments still held	0
Net derivatives [Member]
Liabilities:
Beginning Balance	3,441	(242)
Total gains/(losses) (realized and unrealized)	(4,384)	10,304
Purchases	0	0
Sales	0	0
Settlements	3,373	2,558
Issuances	186	554
Net transfers into/ (out of) Level 3	3,797	(1,417)
Ending Balance	6,413	11,757
Change in unrealized gains/ (losses) relating to instruments still held	1,347	(8,135)
Loans [Member]
Liabilities:
Beginning Balance	378	10,469
Total gains/(losses) (realized and unrealized)	189	(345)
Purchases	(323)	(2,240)
Sales	0	1,033
Settlements	0	(1,077)
Issuances	0	0
Net transfers into/ (out of) Level 3	792	(96)
Ending Balance	1,036	7,744
Change in unrealized gains/ (losses) relating to instruments still held	(189)	345
Other secured financings [Member]
Liabilities:
Beginning Balance	418	544
Total gains/(losses) (realized and unrealized)	(8)	(6)
Purchases	0	0
Sales	0	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	(323)	0
Ending Balance	87	538
Change in unrealized gains/ (losses) relating to instruments still held	11	0
Corporate equity securities [Member]
Assets:
Beginning Balance	21,739	40,906
Total gains/(losses) (realized and unrealized)	532	3,071
Purchases	847	2,087
Sales	(145)	0
Settlements	(186)	0
Issuances	0	0
Net transfers into/ (out of) Level 3	(2,207)	(15,524)
Ending Balance	20,580	30,540
Change in unrealized gains/(losses) relating to instruments still held	362	3,560
Corporate debt securities [Member]
Assets:
Beginning Balance	25,005	25,876
Total gains/(losses) (realized and unrealized)	(1,793)	(2,602)
Purchases	3,002	15,337
Sales	(3,157)	(15,129)
Settlements	(1,207)	(111)
Issuances	0	0
Net transfers into/ (out of) Level 3	11,617	2,263
Ending Balance	33,467	25,634
Change in unrealized gains/(losses) relating to instruments still held	(1,662)	(2,540)
CDOs and CLOs [Member]
Assets:
Beginning Balance	54,354	85,092
Total gains/(losses) (realized and unrealized)	(7,594)	(16,573)
Purchases	8,663	1,021
Sales	(22,633)	(20,178)
Settlements	(45)	(463)
Issuances	0	0
Net transfers into/ (out of) Level 3	12,609	18,449
Ending Balance	45,354	67,348
Change in unrealized gains/(losses) relating to instruments still held	(8,525)	(17,003)
Sovereign obligations [Member]
Assets:
Beginning Balance		120
Total gains/(losses) (realized and unrealized)		(1)
Purchases		0
Sales		0
Settlements		0
Issuances		0
Net transfers into/ (out of) Level 3		0
Ending Balance		119
Change in unrealized gains/(losses) relating to instruments still held		(1)
Municipal securities [Member]
Assets:
Beginning Balance	27,257
Total gains/(losses) (realized and unrealized)	(636)
Purchases	0
Sales	(67)
Settlements	0
Issuances	0
Net transfers into/ (out of) Level 3	0
Ending Balance	26,554
Change in unrealized gains/(losses) relating to instruments still held	(641)
RMBS [Member]
Assets:
Beginning Balance	38,772	70,263
Total gains/(losses) (realized and unrealized)	(253)	(4,548)
Purchases	263	62,844
Sales	(12,411)	(64,926)
Settlements	(210)	(114)
Issuances	0	0
Net transfers into/ (out of) Level 3	13,098	4,500
Ending Balance	39,259	68,019
Change in unrealized gains/(losses) relating to instruments still held	(440)	(3,358)
CMBS [Member]
Assets:
Beginning Balance	20,580	14,326
Total gains/(losses) (realized and unrealized)	(1,420)	(971)
Purchases	0	2,962
Sales	(412)	0
Settlements	0	(878)
Issuances	0	0
Net transfers into/ (out of) Level 3	1,905	6,555
Ending Balance	20,653	21,994
Change in unrealized gains/(losses) relating to instruments still held	(1,421)	(1,387)
Other ABS [Member]
Assets:
Beginning Balance	40,911	42,925
Total gains/(losses) (realized and unrealized)	(1,788)	1,662
Purchases	3,553	15,425
Sales	(299)	(2,100)
Settlements	(3,335)	(1)
Issuances	0	0
Net transfers into/ (out of) Level 3	(1,340)	(24,787)
Ending Balance	37,702	33,124
Change in unrealized gains/(losses) relating to instruments still held	(1,717)	1,679
Loans and other receivables [Member]
Assets:
Beginning Balance	81,872	189,289
Total gains/(losses) (realized and unrealized)	4,950	(5,772)
Purchases	9,489	181,264
Sales	(9,778)	(114,667)
Settlements	(7,764)	(95,354)
Issuances	0	0
Net transfers into/ (out of) Level 3	(25,597)	682
Ending Balance	53,172	155,442
Change in unrealized gains/(losses) relating to instruments still held	836	(9,113)
Investments at fair value [Member]
Assets:
Beginning Balance	96,369	53,120
Total gains/(losses) (realized and unrealized)	(2,199)	(16,515)
Purchases	0	1,187
Sales	(10,119)	0
Settlements	(266)	(273)
Issuances	0	0
Net transfers into/ (out of) Level 3	0	26,063
Ending Balance	83,785	63,582
Change in unrealized gains/(losses) relating to instruments still held	$ (176)	$ (16,515)