Fair Value Disclosures - Summary of Changes in Fair Value of Financial Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Thousands	12 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2014
Assets:
Total gains/(losses) (realized and unrealized)	$ (128,500)	$ (34,300)	$ (28,600)
Liabilities:
Total gains/ losses (realized and unrealized)	1,900	8,300	(6,000)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	38	38	38
Total gains/ losses (realized and unrealized)	0	0	0
Purchases	0	0	0
Sales	313	0	0
Settlements	(38)	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	0	0
Ending Balance	313	38	38
Change in unrealized gains/ (losses) relating to instruments still held	0	0	0
Corporate debt securities [Member]
Liabilities:
Beginning Balance	0	223	0
Total gains/ losses (realized and unrealized)	(27)	(110)	(149)
Purchases	0	(6,804)	(565)
Sales	550	6,691	960
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	0	(23)
Ending Balance	523	0	223
Change in unrealized gains/ (losses) relating to instruments still held	0	0	(8)
Net derivatives [Member]
Liabilities:
Beginning Balance	(242)	(4,638)	6,905
Total gains/ losses (realized and unrealized)	(1,760)	(7,310)	15,055
Purchases	0	(6,705)	(24,682)
Sales	11,101	13,522	1,094
Settlements	31	37	322
Issuances	2,067	2,437	0
Net transfers into/ (out of) Level 3	(7,756)	2,415	(3,332)
Ending Balance	3,441	(242)	(4,638)
Change in unrealized gains/ (losses) relating to instruments still held	(6,458)	4,754	(15,615)
Loans [Member]
Liabilities:
Beginning Balance	10,469	14,450	22,462
Total gains/ losses (realized and unrealized)	0	(163)	0
Purchases	0	(2,059)	(18,332)
Sales	378	229	11,338
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(10,469)	(1,988)	(1,018)
Ending Balance	378	10,469	14,450
Change in unrealized gains/ (losses) relating to instruments still held	0	104	0
Other secured financings [Member]
Liabilities:
Beginning Balance	544	30,825	8,711
Total gains/ losses (realized and unrealized)	(126)	0	0
Purchases	0	0	0
Sales	0	0	0
Settlements	0	(15,704)	(17,525)
Issuances	0	36,995	39,639
Net transfers into/ (out of) Level 3	0	(51,572)	0
Ending Balance	418	544	30,825
Change in unrealized gains/ (losses) relating to instruments still held	(126)	0	0
Embedded conversion option [Member]
Liabilities:
Beginning Balance	0	693	9,574
Total gains/ losses (realized and unrealized)		(693)	(8,881)
Purchases		0	0
Sales		0	0
Settlements		0	0
Issuances		0	0
Net transfers into/ (out of) Level 3		0	0
Ending Balance		0	693
Change in unrealized gains/ (losses) relating to instruments still held		693	8,881
Corporate equity securities [Member]
Assets:
Beginning Balance	40,906	20,964	9,884
Total gains/(losses) (realized and unrealized)	(8,463)	11,154	957
Purchases	3,365	21,385	18,138
Sales	(49)	(6,391)	(12,826)
Settlements	(671)	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(13,349)	(6,206)	4,811
Ending Balance	21,739	40,906	20,964
Change in unrealized gains/(losses) relating to instruments still held	291	11,424	2,324
Corporate debt securities [Member]
Assets:
Beginning Balance	25,876	22,766	25,666
Total gains/(losses) (realized and unrealized)	(16,230)	(11,013)	6,629
Purchases	27,242	21,534	38,316
Sales	(29,347)	(14,636)	(40,328)
Settlements	(7,223)	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	24,687	7,225	(7,517)
Ending Balance	25,005	25,876	22,766
Change in unrealized gains/(losses) relating to instruments still held	(18,799)	(9,443)	8,982
CDOs and CLOs [Member]
Assets:
Beginning Balance	85,092	124,650	37,216
Total gains/(losses) (realized and unrealized)	(14,918)	(66,332)	(6,386)
Purchases	52,316	104,998	204,337
Sales	(69,394)	(107,381)	(181,757)
Settlements	(2,750)	(5,754)	(1,297)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	4,008	34,911	72,537
Ending Balance	54,354	85,092	124,650
Change in unrealized gains/(losses) relating to instruments still held	(7,628)	(48,514)	(1,141)
Municipal securities [Member]
Assets:
Beginning Balance	0	0
Total gains/(losses) (realized and unrealized)	(1,462)	10
Purchases	0	0
Sales	0	0
Settlements	0	(21,551)
Issuances	0	0
Net transfers into/ (out of) Level 3	28,719	21,541
Ending Balance	27,257	0	0
Change in unrealized gains/(losses) relating to instruments still held	(1,462)	0
Sovereign obligations [Member]
Assets:
Beginning Balance	120	0
Total gains/(losses) (realized and unrealized)	5	47
Purchases	0	1,032
Sales	(125)	(1,031)
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	72
Ending Balance	0	120	0
Change in unrealized gains/(losses) relating to instruments still held	0	39
US government and federal agency securities [Member]
Assets:
Beginning Balance		0	0
Total gains/(losses) (realized and unrealized)			13
Purchases			2,505
Sales			(2,518)
Settlements			0
Issuances			0
Net transfers into/ (out of) Level 3			0
Ending Balance			0
Change in unrealized gains/(losses) relating to instruments still held			0
Residential mortgage-backed securities [Member]
Assets:
Beginning Balance	70,263	82,557	105,492
Total gains/(losses) (realized and unrealized)	(9,612)	(12,951)	(9,870)
Purchases	623	18,961	42,632
Sales	(12,249)	(31,762)	(61,689)
Settlements	(931)	(597)	(1,847)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(9,322)	14,055	7,839
Ending Balance	38,772	70,263	82,557
Change in unrealized gains/(losses) relating to instruments still held	(1,095)	(4,498)	(4,679)
Commercial mortgage-backed securities [Member]
Assets:
Beginning Balance	14,326	26,655	17,568
Total gains/(losses) (realized and unrealized)	(7,550)	(3,813)	(4,237)
Purchases	3,132	3,480	49,159
Sales	(2,024)	(10,146)	(51,360)
Settlements	(2,229)	(6,861)	(782)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	14,925	5,011	16,307
Ending Balance	20,580	14,326	26,655
Change in unrealized gains/(losses) relating to instruments still held	(7,243)	(3,205)	(2,384)
Other asset-backed securities [Member]
Assets:
Beginning Balance	42,925	2,294	12,611
Total gains/(losses) (realized and unrealized)	(14,381)	(990)	1,784
Purchases	133,986	42,922	4,987
Sales	(102,952)	(1,299)	(18,002)
Settlements	(8,769)	(2)	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(9,898)	0	914
Ending Balance	40,911	42,925	2,294
Change in unrealized gains/(losses) relating to instruments still held	(18,056)	(254)	1,484
Loans and other receivables [Member]
Assets:
Beginning Balance	189,289	97,258	145,890
Total gains/(losses) (realized and unrealized)	(42,566)	(14,755)	(31,311)
Purchases	75,264	792,345	130,169
Sales	(69,262)	(576,536)	(92,140)
Settlements	(46,851)	(124,365)	(60,390)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(24,002)	15,342	5,040
Ending Balance	81,872	189,289	97,258
Change in unrealized gains/(losses) relating to instruments still held	(52,003)	(16,802)	(26,864)
Investments at fair value [Member]
Assets:
Beginning Balance	53,120	53,224	66,931
Total gains/(losses) (realized and unrealized)	(13,278)	64,380	13,781
Purchases	26,228	5,510	32,493
Sales	(542)	(124,852)	(43,286)
Settlements	(1,107)	(4,093)	(1,243)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	31,948	58,951	(15,452)
Ending Balance	96,369	53,120	53,224
Change in unrealized gains/(losses) relating to instruments still held	$ (13,208)	$ (388)	$ (1,876)