Fair Value Disclosures - Level 3 Rollforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2017
Assets:
Total gains/(losses) (realized and unrealized)	$ (27,100)	$ (12,700)	$ (24,600)
Liabilities:
Total gains/(losses) (realized and unrealized)	(44,500)	(33,600)	(1,700)
Corporate equity securities
Assets:
Beginning Balance	51,040	22,009	21,739
Total gains/(losses) (realized and unrealized)	(10,380)	24,023	3,262
Purchases	69,065	31,669	896
Sales	(28,159)	(22,759)	(1,623)
Settlements	(18,208)	(3,977)	52
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(5,057)	75	(2,317)
Ending Balance	58,301	51,040	22,009
Changes in unrealized gains/(losses) included in earnings for instruments still held	(12,821)	22,774	2,515
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Liabilities:
Beginning Balance	0	48	313
Total gains/(losses) (realized and unrealized)	(2,649)	0	60
Purchases	(4,322)	0	(373)
Sales	11,458	0	48
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	(48)	0
Ending Balance	4,487	0	48
Changes in unrealized gains/ (losses) included in earnings for instruments still held	1,928	0	0
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Corporate debt securities
Assets:
Beginning Balance	9,484	26,036	25,005
Total gains/(losses) (realized and unrealized)	(4,860)	(439)	(3,723)
Purchases	8,900	10,352	36,850
Sales	(13,854)	(23,364)	(34,077)
Settlements	(379)	(1,679)	(1,968)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	8,199	(1,422)	3,949
Ending Balance	7,490	9,484	26,036
Changes in unrealized gains/(losses) included in earnings for instruments still held	(6,176)	(2,606)	(3,768)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Liabilities:
Beginning Balance	522	522	523
Total gains/(losses) (realized and unrealized)	(381)	0	(1)
Purchases	(457)	0	0
Sales	0	0	0
Settlements	(524)	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	1,180	0	0
Ending Balance	340	522	522
Changes in unrealized gains/ (losses) included in earnings for instruments still held	383	0	1
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
CDOs and CLOs
Assets:
Beginning Balance	25,815	30,004	54,354
Total gains/(losses) (realized and unrealized)	(2,342)	(14,368)	(19,858)
Purchases	49,658	356,650	112,239
Sales	(38,147)	(353,330)	(110,907)
Settlements	(9,083)	(10,247)	(367)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	(5,820)	17,106	(5,457)
Ending Balance	20,081	25,815	30,004
Changes in unrealized gains/(losses) included in earnings for instruments still held	(974)	(7,605)	(2,262)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Municipal securities
Assets:
Beginning Balance		0	27,257
Total gains/(losses) (realized and unrealized)			(1,547)
Purchases			0
Sales			(25,710)
Settlements			0
Issuances			0
Net transfers into/ (out of) Level 3			0
Ending Balance			0
Changes in unrealized gains/(losses) included in earnings for instruments still held			0
RMBS
Assets:
Beginning Balance	19,603	26,077	38,772
Total gains/(losses) (realized and unrealized)	(1,669)	(6,970)	(10,817)
Purchases	1,954	3,118	6,805
Sales	(2,472)	(12,816)	(26,193)
Settlements	(152)	(513)	(115)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	476	10,707	17,625
Ending Balance	17,740	19,603	26,077
Changes in unrealized gains/(losses) included in earnings for instruments still held	(530)	521	(7,201)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
CMBS
Assets:
Beginning Balance	10,886	12,419	20,580
Total gains/(losses) (realized and unrealized)	(2,888)	(2,186)	(5,346)
Purchases	206	1,436	3,275
Sales	(2,346)	(471)	(5,263)
Settlements	(5,317)	(16,624)	(1,018)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	5,569	16,312	191
Ending Balance	6,110	10,886	12,419
Changes in unrealized gains/(losses) included in earnings for instruments still held	(2,366)	(4,000)	(6,976)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Liabilities:
Beginning Balance	0	105	0
Total gains/(losses) (realized and unrealized)	35	(105)	105
Purchases	0	0	0
Sales	0	0	0
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	0	0
Ending Balance	35	0	105
Changes in unrealized gains/ (losses) included in earnings for instruments still held	35	0	(105)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Other ABS
Assets:
Beginning Balance	53,175	61,129	40,911
Total gains/(losses) (realized and unrealized)	433	(9,934)	(17,705)
Purchases	104,097	706,846	77,508
Sales	(73,335)	(677,220)	(8,613)
Settlements	(51,374)	(27,641)	(25,799)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	9,567	(5)	(5,173)
Ending Balance	42,563	53,175	61,129
Changes in unrealized gains/(losses) included in earnings for instruments still held	(98)	(5,283)	(12,562)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Loans and other receivables
Assets:
Beginning Balance	46,985	47,304	81,872
Total gains/(losses) (realized and unrealized)	(5,505)	(5,137)	24,794
Purchases	57,403	149,228	63,768
Sales	(48,350)	(130,832)	(53,095)
Settlements	(5,068)	(15,311)	(34,622)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	18,775	1,733	(35,413)
Ending Balance	64,240	46,985	47,304
Changes in unrealized gains/(losses) included in earnings for instruments still held	(3,319)	(8,457)	17,451
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Investments at fair value
Assets:
Beginning Balance	113,831	93,454	96,369
Total gains/(losses) (realized and unrealized)	113	2,353	6,361
Purchases	240	34,648	1,981
Sales	(38,446)	(17,570)	(10,157)
Settlements	0	0	(1,100)
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	946	0
Ending Balance	75,738	113,831	93,454
Changes in unrealized gains/(losses) included in earnings for instruments still held	2,964	1,759	8,385
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Securities purchased under agreements to resell
Assets:
Beginning Balance	0
Total gains/(losses) (realized and unrealized)	0
Purchases	0
Sales	0
Settlements	0
Issuances	25,000
Net transfers into/ (out of) Level 3	0
Ending Balance	25,000	0
Changes in unrealized gains/(losses) included in earnings for instruments still held	0
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Loans
Liabilities:
Beginning Balance	6,376	3,486	378
Total gains/(losses) (realized and unrealized)	(1,382)	84	196
Purchases	(2,573)	(4,626)	(385)
Sales	6,494	7,432	2,485
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	548	0	812
Ending Balance	9,463	6,376	3,486
Changes in unrealized gains/ (losses) included in earnings for instruments still held	1,382	(28)	(2,639)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Net derivatives
Liabilities:
Beginning Balance	21,614	6,746	3,441
Total gains/(losses) (realized and unrealized)	(21,452)	(3,237)	(1,638)
Purchases	(4,323)	(17)	0
Sales	36,144	14,920	0
Settlements	2,227	(1,335)	5,558
Issuances	0	0	456
Net transfers into/ (out of) Level 3	42,958	4,537	(1,071)
Ending Balance	77,168	21,614	6,746
Changes in unrealized gains/ (losses) included in earnings for instruments still held	12,098	(646)	(17,740)
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0	0
Other secured financings
Liabilities:
Beginning Balance		0	418
Total gains/(losses) (realized and unrealized)			(418)
Purchases			0
Sales			0
Settlements			0
Issuances			0
Net transfers into/ (out of) Level 3			0
Ending Balance			0
Changes in unrealized gains/ (losses) included in earnings for instruments still held			0
Long-term debt
Liabilities:
Beginning Balance	200,745	0
Total gains/(losses) (realized and unrealized)	(18,662)	(30,347)
Purchases	0	0
Sales	0	0
Settlements	(11,250)	0
Issuances	348,275	84,860
Net transfers into/ (out of) Level 3	(39,039)	146,232
Ending Balance	480,069	200,745	$ 0
Changes in unrealized gains/ (losses) included in earnings for instruments still held	29,656	10,951
Changes in unrealized gains/ (losses) included in other comprehensive income for instruments still held	$ (10,993)	$ 19,396