Fair Value Disclosures - Level 3 Rollforwards (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019
Assets:
Total gains/losses (realized and unrealized)	$ 7,200	$ (6,900)	$ (58,100)	$ (200)
Liabilities:
Total gains/losses (realized and unrealized)	124,300	(12,800)	(50,100)	(55,800)
Corporate equity securities
Assets:
Beginning Balance	76,100	59,307	58,301	51,040
Total gains/losses (realized and unrealized)	(588)	12,542	(3,793)	16,381
Purchases	699	16,508	3,299	23,172
Sales	0	(17,502)	(13,555)	(25,431)
Settlements	0	0	0	(669)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	1,619	(20,255)	33,578	(13,893)
Ending Balance	77,830	50,600	77,830	50,600
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(588)	12,062	(654)	14,953
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Liabilities:
Beginning Balance	4,190	221	4,487	0
Total gains/losses (realized and unrealized)	(12)	401	258	401
Purchases	0	(221)	(567)	0
Sales	0	0	0	0
Settlements	0	(190)	0	(190)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	189	0	189	0
Ending Balance	4,367	211	4,367	211
For instruments still held, changes in unrealized gains/(losses) included in Earnings	12	(35)	98	(35)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Corporate debt securities
Assets:
Beginning Balance	25,178	7,429	7,490	9,484
Total gains/losses (realized and unrealized)	(889)	(3,072)	(162)	(4,904)
Purchases	4	1,175	285	6,080
Sales	(394)	(1,942)	(489)	(10,544)
Settlements	0	(85)	(602)	(553)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(630)	5,783	16,747	9,725
Ending Balance	23,269	9,288	23,269	9,288
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(881)	(3,047)	(591)	(5,325)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Liabilities:
Beginning Balance	163	669	340	522
Total gains/losses (realized and unrealized)	(15)	(650)	(261)	(867)
Purchases	0	(34)	(325)	0
Sales	0	0	394	0
Settlements	0	(369)	0	(524)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	1,586	0	2,071
Ending Balance	148	1,202	148	1,202
For instruments still held, changes in unrealized gains/(losses) included in Earnings	15	649	20	867
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
CDOs and CLOs
Assets:
Beginning Balance	23,139	16,195	20,081	25,815
Total gains/losses (realized and unrealized)	3,796	(1,514)	(8,651)	(5,892)
Purchases	39	0	10,883	48,112
Sales	(7,539)	0	(20,935)	(43,230)
Settlements	(2,075)	0	(5,675)	(275)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	10,576	6,454	32,233	(3,395)
Ending Balance	27,936	21,135	27,936	21,135
For instruments still held, changes in unrealized gains/(losses) included in Earnings	385	(1,503)	(20,218)	(5,614)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
RMBS
Assets:
Beginning Balance	22,339	17,266	17,740	19,603
Total gains/losses (realized and unrealized)	1,240	(1,917)	(1,347)	(2,573)
Purchases	0	0	7,625	2,166
Sales	0	(65)	0	(2,022)
Settlements	(774)	(22)	(496)	(171)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	5,512	2,667	4,795	926
Ending Balance	28,317	17,929	28,317	17,929
For instruments still held, changes in unrealized gains/(losses) included in Earnings	1,262	(1,435)	(1,811)	(2,166)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
CMBS
Assets:
Beginning Balance	4,461	12,530	6,110	10,886
Total gains/losses (realized and unrealized)	202	(2,003)	232	(2,196)
Purchases	0	0	0	11
Sales	0	(1,703)	0	(2,023)
Settlements	0	(3,362)	(1,785)	(6,638)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	0	106	5,422
Ending Balance	4,663	5,462	4,663	5,462
For instruments still held, changes in unrealized gains/(losses) included in Earnings	198	(3,143)	807	(4,326)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Liabilities:
Beginning Balance	140	0	35
Total gains/losses (realized and unrealized)	0	0	0
Purchases	(140)	0	(35)
Sales	35	35	35	35
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	0	0
Ending Balance	35	35	35	35
For instruments still held, changes in unrealized gains/(losses) included in Earnings	0	0	0
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0
Other ABS
Assets:
Beginning Balance	86,062	43,185	42,563	53,175
Total gains/losses (realized and unrealized)	(1,585)	(1,689)	(3,495)	(929)
Purchases	3,313	13,497	29,096	14,698
Sales	0	(6,975)	(664)	(2,494)
Settlements	(7,442)	(5,500)	(22,125)	(30,623)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(17,011)	(7,920)	17,962	771
Ending Balance	63,337	34,598	63,337	34,598
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(5,101)	(1,068)	(13,012)	(961)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Loans and other receivables
Assets:
Beginning Balance	68,429	98,484	64,240	46,985
Total gains/losses (realized and unrealized)	8,302	(2,847)	(7,093)	3,933
Purchases	18,492	26,921	259,982	178,069
Sales	(13,897)	(33,409)	(208,958)	(166,496)
Settlements	(355)	(1,287)	(6,979)	(8,379)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	24,463	(12,299)	4,242	21,451
Ending Balance	105,434	75,563	105,434	75,563
For instruments still held, changes in unrealized gains/(losses) included in Earnings	8,633	(2,392)	(6,216)	682
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Investments at fair value
Assets:
Beginning Balance	63,959	103,833	75,738	113,831
Total gains/losses (realized and unrealized)	(3,257)	(6,407)	(33,753)	(3,971)
Purchases	2,182	240	21,067	31,583
Sales	0	(296)	(168)	(296)
Settlements	(13,003)	0	(13,003)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	35,135	0	(8,642)
Ending Balance	49,881	132,505	49,881	132,505
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(4,406)	(6,407)	(35,601)	(3,971)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Securities purchased under agreements to resell
Assets:
Beginning Balance		25,000	25,000	0
Total gains/losses (realized and unrealized)		0	0	0
Purchases		0	0	0
Sales		0	0	0
Settlements		0	(25,000)	0
Issuances		0	0	25,000
Net transfers into/ (out of) Level 3		0	0	0
Ending Balance	0	25,000	0	25,000
For instruments still held, changes in unrealized gains/(losses) included in Earnings		0	0	0
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income		0	0	0
Loans
Liabilities:
Beginning Balance	10,674	9,428	9,463	6,376
Total gains/losses (realized and unrealized)	6,636	(520)	2,986	(1,342)
Purchases	(23,001)	(10,281)	(5,760)	(8,553)
Sales	3,558	5,384	38,531	9,929
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	48,727	12,619	1,374	10,220
Ending Balance	46,594	16,630	46,594	16,630
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(6,591)	531	(3,366)	1,583
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Net derivatives
Liabilities:
Beginning Balance	45,131	47,449	77,168	21,614
Total gains/losses (realized and unrealized)	(12,175)	(19,519)	(63,367)	(48,746)
Purchases	(1,404)	0	(6,732)	(2,829)
Sales	13,089	6,766	26,656	16,313
Settlements	(648)	(14)	(1,567)	1,609
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(21,568)	16,081	(9,733)	62,802
Ending Balance	22,425	50,763	22,425	50,763
For instruments still held, changes in unrealized gains/(losses) included in Earnings	12,007	18,507	60,257	40,052
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Other secured financings
Liabilities:
Beginning Balance	0		0
Total gains/losses (realized and unrealized)	(617)		(617)
Purchases	0		0
Sales	0		0
Settlements	0		0
Issuances	4,019		4,019
Net transfers into/ (out of) Level 3	0		0
Ending Balance	3,402		3,402
For instruments still held, changes in unrealized gains/(losses) included in Earnings	617		617
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0		0
Long-term debt
Liabilities:
Beginning Balance	497,040	236,562	480,069	200,745
Total gains/losses (realized and unrealized)	130,463	7,455	10,851	(5,286)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	(2,000)	(11,250)
Issuances	5,749	114,641	202,046	204,710
Net transfers into/ (out of) Level 3	(2,992)	(10,595)	(60,706)	(40,856)
Ending Balance	630,260	348,063	630,260	348,063
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(42,163)	(8,162)	(28,153)	(4,517)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	$ (88,300)	$ 706	$ 17,302	$ 9,804