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. 29, 2016	Feb. 28, 2015
Assets:
Total gains/(losses) (realized and unrealized)	$ (42,200)	$ (25,200)
Liabilities:
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(10,000)	(6,900)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	38	38
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	0	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	0
Ending Balance	38	38
Change in unrealized gains/ (losses) relating to instruments still held	0	0
Corporate debt securities [Member]
Liabilities:
Beginning Balance		223
Net gains/(losses) on Level 3 liabilities (realized and unrealized)		(115)
Purchases		(6,683)
Sales		6,698
Settlements		0
Issuances		0
Net transfers into/ (out of) Level 3		(123)
Ending Balance		0
Change in unrealized gains/ (losses) relating to instruments still held		0
Net derivatives [Member]
Liabilities:
Beginning Balance	(242)	(4,638)
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	10,304	6,938
Purchases	0	0
Sales	0	0
Settlements	2,558	(58)
Issuances	554	1,072
Net transfers into/ (out of) Level 3	(1,417)	0
Ending Balance	11,757	3,314
Change in unrealized gains/ (losses) relating to instruments still held	(8,135)	(8,771)
Loans [Member]
Liabilities:
Beginning Balance	10,469	14,450
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(345)	(39)
Purchases	(2,240)	(2,877)
Sales	1,033	825
Settlements	(1,077)	0
Issuances	0	0
Net transfers into/ (out of) Level 3	(96)	(3,032)
Ending Balance	7,744	9,327
Change in unrealized gains/ (losses) relating to instruments still held	345	39
Other secured financings [Member]
Liabilities:
Beginning Balance	544	30,825
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(6)	0
Purchases	0	0
Sales	0	0
Settlements	0	(2,218)
Issuances	0	36,995
Net transfers into/ (out of) Level 3	0	0
Ending Balance	538	65,602
Change in unrealized gains/ (losses) relating to instruments still held	0	0
Embedded conversion option [Member]
Liabilities:
Beginning Balance		693
Net gains/(losses) on Level 3 liabilities (realized and unrealized)		132
Purchases		0
Sales		0
Settlements		0
Issuances		0
Net transfers into/ (out of) Level 3		0
Ending Balance		825
Change in unrealized gains/ (losses) relating to instruments still held		(132)
Corporate equity securities [Member]
Assets:
Beginning Balance	40,906	20,964
Total gains/(losses) (realized and unrealized)	3,071	63
Purchases	2,087	0
Sales	0	(168)
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	(15,524)	(2,649)
Ending Balance	30,540	18,210
Change in unrealized gains/(losses) relating to instruments still held	3,560	243
Corporate debt securities [Member]
Assets:
Beginning Balance	25,876	22,766
Total gains/(losses) (realized and unrealized)	(2,602)	(311)
Purchases	15,337	469
Sales	(15,129)	(533)
Settlements	(111)	0
Issuances	0	0
Net transfers into/ (out of) Level 3	2,263	2,404
Ending Balance	25,634	24,795
Change in unrealized gains/(losses) relating to instruments still held	(2,540)	43
Collateralized debt obligations [Member]
Assets:
Beginning Balance	85,092	124,650
Total gains/(losses) (realized and unrealized)	(16,573)	(17,642)
Purchases	1,021	0
Sales	(20,178)	(13,519)
Settlements	(463)	(1,296)
Issuances	0	0
Net transfers into/ (out of) Level 3	18,449	4,644
Ending Balance	67,348	96,837
Change in unrealized gains/(losses) relating to instruments still held	(17,003)	(17,506)
Sovereign obligations [Member]
Assets:
Beginning Balance	120	0
Total gains/(losses) (realized and unrealized)	(1)	13
Purchases	0	0
Sales	0	(1)
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	321
Ending Balance	119	333
Change in unrealized gains/(losses) relating to instruments still held	(1)	12
Residential mortgage-backed securities [Member]
Assets:
Beginning Balance	70,263	82,557
Total gains/(losses) (realized and unrealized)	(4,548)	(2,863)
Purchases	62,844	2,100
Sales	(64,926)	(1,375)
Settlements	(114)	(23)
Issuances	0	0
Net transfers into/ (out of) Level 3	4,500	(443)
Ending Balance	68,019	79,953
Change in unrealized gains/(losses) relating to instruments still held	(3,358)	783
Commercial mortgage-backed securities [Member]
Assets:
Beginning Balance	14,326	26,655
Total gains/(losses) (realized and unrealized)	(971)	(531)
Purchases	2,962	0
Sales	0	(382)
Settlements	(878)	(6,864)
Issuances	0	0
Net transfers into/ (out of) Level 3	6,555	5,751
Ending Balance	21,994	24,629
Change in unrealized gains/(losses) relating to instruments still held	(1,387)	(1,369)
Other asset-backed securities [Member]
Assets:
Beginning Balance	42,925	2,294
Total gains/(losses) (realized and unrealized)	1,662	(167)
Purchases	15,425	26
Sales	(2,100)	(1)
Settlements	(1)	0
Issuances	0	0
Net transfers into/ (out of) Level 3	(24,787)	4,994
Ending Balance	33,124	7,146
Change in unrealized gains/(losses) relating to instruments still held	1,679	(167)
Loans and other receivables [Member]
Assets:
Beginning Balance	189,289	97,258
Total gains/(losses) (realized and unrealized)	(5,772)	(5,033)
Purchases	181,264	40,019
Sales	(114,667)	(16,122)
Settlements	(95,354)	(15,448)
Issuances	0	0
Net transfers into/ (out of) Level 3	682	10,736
Ending Balance	155,442	111,410
Change in unrealized gains/(losses) relating to instruments still held	(9,113)	(3,262)
Investments at fair value [Member]
Assets:
Beginning Balance	53,120	53,224
Total gains/(losses) (realized and unrealized)	(16,515)	1,256
Purchases	1,187	5,010
Sales	0	(184)
Settlements	(273)	(277)
Issuances	0	0
Net transfers into/ (out of) Level 3	26,063	69,203
Ending Balance	63,582	128,232
Change in unrealized gains/(losses) relating to instruments still held	$ (16,515)	$ 1,262