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, 2016	May 31, 2015	May 31, 2016	May 31, 2015
Assets:
Total gains/(losses) (realized and unrealized)	$ (21,400)	$ 2,400	$ (51,900)	$ (17,300)
Liabilities:
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	300	5,000	(9,500)	(1,900)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	38	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)	0	(38)	0
Ending Balance	0	38	0	38
Change in unrealized gains/ (losses) relating to instruments still held	0	0	0	0
Corporate debt securities [Member]
Liabilities:
Beginning Balance		0		223
Net gains/(losses) on Level 3 liabilities (realized and unrealized)		339		225
Purchases		0		(6,677)
Sales		113		6,804
Settlements		0		0
Issuances		0		0
Net transfers into/ (out of) Level 3		0		(123)
Ending Balance		452		452
Change in unrealized gains/ (losses) relating to instruments still held		(339)		(339)
Net derivatives [Member]
Liabilities:
Beginning Balance	11,757	3,314	(242)	(4,638)
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	3	(4,912)	10,075	1,925
Purchases	0	(11,963)	0	(8,848)
Sales	0	0	0	120
Settlements	(83)	12,078	(46)	8,395
Issuances	451	389	1,005	1,460
Net transfers into/ (out of) Level 3	(7,704)	(492)	(6,368)	0
Ending Balance	4,424	(1,586)	4,424	(1,586)
Change in unrealized gains/ (losses) relating to instruments still held	(3)	4,912	(11,008)	(3,586)
Loans [Member]
Liabilities:
Beginning Balance	7,744	9,327	10,469	14,450
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(261)	(332)	(541)	(277)
Purchases	0	(1,170)	(2,240)	(759)
Sales	0	350	1,033	350
Settlements	(71)	2,557	(1,149)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(5,516)	0	(5,676)	(3,032)
Ending Balance	1,896	10,732	1,896	10,732
Change in unrealized gains/ (losses) relating to instruments still held	261	332	250	277
Other secured financings [Member]
Liabilities:
Beginning Balance	538	65,602	544	30,825
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(70)	0	(76)	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	(9,542)	0	(11,760)
Issuances	0	0	0	36,995
Net transfers into/ (out of) Level 3	0	0	0	0
Ending Balance	468	56,060	468	56,060
Change in unrealized gains/ (losses) relating to instruments still held	70	0	76	0
Embedded conversion option [Member]
Liabilities:
Beginning Balance		825		693
Net gains/(losses) on Level 3 liabilities (realized and unrealized)		(100)		32
Purchases		0		0
Sales		0		0
Settlements		0		0
Issuances		0		0
Net transfers into/ (out of) Level 3		0		0
Ending Balance		725		725
Change in unrealized gains/ (losses) relating to instruments still held		100		(32)
Corporate equity securities [Member]
Assets:
Beginning Balance	30,540	18,210	40,906	20,964
Total gains/(losses) (realized and unrealized)	(927)	8,030	1,571	7,066
Purchases	200	0	2,287	1,469
Sales	(508)	(73)	(508)	(262)
Settlements	(2,455)	0	(2,455)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	21,966	(5,620)	7,015	(8,690)
Ending Balance	48,816	20,547	48,816	20,547
Change in unrealized gains/(losses) relating to instruments still held	(849)	8,073	2,080	7,077
Corporate debt securities [Member]
Assets:
Beginning Balance	25,634	24,795	25,876	22,766
Total gains/(losses) (realized and unrealized)	474	(532)	(2,378)	(796)
Purchases	15	2,183	16,564	3,095
Sales	(789)	(2,368)	(16,613)	(3,445)
Settlements	0	0	(245)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(1,221)	7,839	909	10,297
Ending Balance	24,113	31,917	24,113	31,917
Change in unrealized gains/(losses) relating to instruments still held	347	(922)	(2,474)	(929)
Collateralized debt obligations [Member]
Assets:
Beginning Balance	67,348	96,837	85,092	124,650
Total gains/(losses) (realized and unrealized)	1,797	(5,120)	(20,455)	(17,229)
Purchases	943	29,021	24,024	66,246
Sales	(21,233)	(25,430)	(43,696)	(59,532)
Settlements	0	0	(473)	(147)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	3,855	(6,301)	8,218	(24,981)
Ending Balance	52,710	89,007	52,710	89,007
Change in unrealized gains/(losses) relating to instruments still held	2,534	(2,328)	(12,002)	(8,989)
Sovereign obligations [Member]
Assets:
Beginning Balance	119	333	120
Total gains/(losses) (realized and unrealized)	1	(12)	0
Purchases	0	320	0
Sales	0	(641)	0
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	0	0
Ending Balance	120	0	120	0
Change in unrealized gains/(losses) relating to instruments still held	1	0	0
Residential mortgage-backed securities [Member]
Assets:
Beginning Balance	68,019	79,953	70,263	82,557
Total gains/(losses) (realized and unrealized)	(4,915)	(1,820)	(8,337)	(3,735)
Purchases	3,422	8,733	1,483	24,083
Sales	(2,837)	(4,915)	(4,843)	(18,899)
Settlements	(122)	(323)	(235)	(477)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(259)	7,067	4,977	5,166
Ending Balance	63,308	88,695	63,308	88,695
Change in unrealized gains/(losses) relating to instruments still held	(2,233)	315	(4,011)	(822)
Commercial mortgage-backed securities [Member]
Assets:
Beginning Balance	21,994	24,629	14,326	26,655
Total gains/(losses) (realized and unrealized)	(1,140)	(789)	(2,589)	(1,124)
Purchases	0	1,256	2,951	4,685
Sales	0	(9,237)	(2,023)	(12,128)
Settlements	(311)	(173)	(1,208)	(6,971)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	4,440	2,176	13,526	6,745
Ending Balance	24,983	17,862	24,983	17,862
Change in unrealized gains/(losses) relating to instruments still held	(1,306)	(759)	(3,140)	(496)
Other asset-backed securities [Member]
Assets:
Beginning Balance	33,124	7,146	42,925	2,294
Total gains/(losses) (realized and unrealized)	(7,284)	(19)	(202)	(258)
Purchases	3,549	8,322	64,833	8,385
Sales	(1,068)	(80)	(74,690)	(79)
Settlements	(52)	(270)	(4,713)	(207)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	14,764	(3,242)	14,880	1,722
Ending Balance	43,033	11,857	43,033	11,857
Change in unrealized gains/(losses) relating to instruments still held	(7,275)	41	(7,134)	(97)
Loans and other receivables [Member]
Assets:
Beginning Balance	155,442	111,410	189,289	97,258
Total gains/(losses) (realized and unrealized)	(7,792)	(748)	(13,376)	(5,795)
Purchases	20,836	40,602	203,990	71,865
Sales	(13,347)	(26,335)	(127,944)	(29,184)
Settlements	(55,541)	(16,314)	(150,975)	(33,895)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	4,801	141	3,415	8,507
Ending Balance	104,399	108,756	104,399	108,756
Change in unrealized gains/(losses) relating to instruments still held	(6,231)	(669)	(15,693)	(3,166)
Investments at fair value [Member]
Assets:
Beginning Balance	63,582	128,232	53,120	53,224
Total gains/(losses) (realized and unrealized)	(1,574)	3,380	(6,090)	4,615
Purchases	40	73	1,227	5,270
Sales	0	(78)	0	(427)
Settlements	(283)	(264)	(555)	(541)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(4,000)	0	10,063	69,202
Ending Balance	57,765	131,343	57,765	131,343
Change in unrealized gains/(losses) relating to instruments still held	$ (6)	$ 3,482	$ 911	$ 4,882