Fair Value Disclosures - Level 3 Rollforwards (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Assets:
Total gains/losses (realized and unrealized)	$ (39,500)	$ 2,000	$ (69,800)	$ 2,700
Liabilities:
Total gains/losses (realized and unrealized)	(124,300)	(14,100)	(144,700)	42,800
Corporate equity securities
Assets:
Beginning Balance	103,643	54,766	58,301	51,040
Total gains/losses (realized and unrealized)	(5,319)	2,353	(12,860)	6,126
Purchases	36	221	2,989	785
Sales	(68)	(179)	(2,017)	(2,031)
Settlements	0	(551)	0	(720)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(22,192)	2,697	29,687	4,107
Ending Balance	76,100	59,307	76,100	59,307
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(5,220)	2,454	(12,787)	7,972
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Liabilities:
Beginning Balance	4,275	78	4,487	0
Total gains/losses (realized and unrealized)	(60)	(74)	216	(76)
Purchases	0	(1,520)	(513)	(1,546)
Sales	0	1,737	0	1,843
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(25)	0	0	0
Ending Balance	4,190	221	4,190	221
For instruments still held, changes in unrealized gains/(losses) included in Earnings	60	0	140	0
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Corporate debt securities
Assets:
Beginning Balance	25,090	10,930	7,490	9,484
Total gains/losses (realized and unrealized)	(1,480)	(587)	1,560	(389)
Purchases	328	180	766	1,545
Sales	(365)	0	(479)	(2,130)
Settlements	(1)	(325)	(602)	(1,177)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	1,606	(2,769)	16,443	96
Ending Balance	25,178	7,429	25,178	7,429
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(1,464)	(588)	1,190	(334)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Liabilities:
Beginning Balance	767	730	340	522
Total gains/losses (realized and unrealized)	(23)	(148)	(27)	(382)
Purchases	(20)	(7)	(150)	(73)
Sales	0	1	0	93
Settlements	0	22	0	22
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(561)	71	0	487
Ending Balance	163	669	163	669
For instruments still held, changes in unrealized gains/(losses) included in Earnings	0	90	5	305
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
CDOs and CLOs
Assets:
Beginning Balance	20,952	32,566	20,081	25,815
Total gains/losses (realized and unrealized)	(12,879)	(1,793)	(14,223)	(2,790)
Purchases	0	0	9,426	4,782
Sales	(8,471)	0	(11,849)	0
Settlements	(1,673)	0	(3,193)	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	25,210	(14,578)	22,897	(11,612)
Ending Balance	23,139	16,195	23,139	16,195
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(16,031)	(1,795)	(17,115)	(2,554)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
RMBS
Assets:
Beginning Balance	16,970	20,963	17,740	19,603
Total gains/losses (realized and unrealized)	(1,773)	(802)	(2,248)	(316)
Purchases	1,380	0	2,062	39
Sales	0	0	0	0
Settlements	(7)	(18)	(10)	(45)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	5,769	(2,877)	4,795	(2,015)
Ending Balance	22,339	17,266	22,339	17,266
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(1,733)	(759)	(2,195)	(271)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
CMBS
Assets:
Beginning Balance	4,264	12,820	6,110	10,886
Total gains/losses (realized and unrealized)	53	(357)	(95)	(180)
Purchases	0	0	0	11
Sales	0	(331)	0	(331)
Settlements	0	(3,238)	(1,660)	(3,278)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	144	3,636	106	5,422
Ending Balance	4,461	12,530	4,461	12,530
For instruments still held, changes in unrealized gains/(losses) included in Earnings	53	(1,292)	(680)	(1,183)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Liabilities:
Beginning Balance	35	70	35
Total gains/losses (realized and unrealized)	0	(70)	0
Purchases	0	0	(35)
Sales	105	0	140
Settlements	0	0	0
Issuances	0	0	0
Net transfers into/ (out of) Level 3	0	0	0
Ending Balance	140	0	140	0
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	41,903	35,886	42,563	53,175
Total gains/losses (realized and unrealized)	(2,380)	3,070	(2,848)	(1,014)
Purchases	11,038	16,531	33,917	25,316
Sales	0	(8,868)	(664)	(13,247)
Settlements	(8,490)	(8,549)	(17,361)	(9,529)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	43,991	5,115	30,455	(11,516)
Ending Balance	86,062	43,185	86,062	43,185
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(5,087)	3,563	(7,226)	(522)
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	54,321	78,051	64,240	46,985
Total gains/losses (realized and unrealized)	(4,891)	(2,753)	(8,600)	2,434
Purchases	45,984	38,780	66,047	77,004
Sales	(46,939)	(13,898)	(76,227)	(33,549)
Settlements	(128)	(2,438)	(6,606)	(3,378)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	20,082	742	29,575	8,988
Ending Balance	68,429	98,484	68,429	98,484
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(4,847)	(1,277)	(11,689)	844
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	55,270	140,812	75,738	113,831
Total gains/losses (realized and unrealized)	(10,805)	2,841	(30,496)	(1,162)
Purchases	400	0	18,885	31,343
Sales	(91)	0	(168)	0
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	19,185	(39,820)	0	(40,179)
Ending Balance	63,959	103,833	63,959	103,833
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(10,805)	2,841	(30,496)	(1,162)
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		0	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		25,000	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	7,859	3,420	9,463	6,376
Total gains/losses (realized and unrealized)	1,015	(191)	1,072	(401)
Purchases	(2,785)	(1,678)	(12,958)	(3,946)
Sales	3,290	1,537	3,290	7,963
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	1,295	6,340	9,807	(564)
Ending Balance	10,674	9,428	10,674	9,428
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(1,015)	364	(1,075)	579
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Net derivatives
Liabilities:
Beginning Balance	110,843	28,975	77,168	21,614
Total gains/losses (realized and unrealized)	(32,744)	(14,760)	(44,729)	(29,079)
Purchases	(10,810)	(25)	(11,088)	(2,829)
Sales	33,196	4,175	38,823	7,259
Settlements	(603)	1,974	(1,010)	2,031
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(54,751)	27,110	(14,033)	48,453
Ending Balance	45,131	47,449	45,131	47,449
For instruments still held, changes in unrealized gains/(losses) included in Earnings	34,259	7,565	32,211	19,607
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0	0	0
Long-term debt
Liabilities:
Beginning Balance	543,463	283,139	480,069	200,745
Total gains/losses (realized and unrealized)	(92,480)	1,163	(101,267)	(12,854)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	(5,585)	0	(11,250)
Issuances	66,916	39,385	175,498	101,872
Net transfers into/ (out of) Level 3	(20,859)	(81,540)	(57,260)	(41,951)
Ending Balance	497,040	236,562	497,040	236,562
For instruments still held, changes in unrealized gains/(losses) included in Earnings	664	(813)	(4,802)	3,827
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	$ 91,816	$ (350)	$ 106,069	$ 9,027