Fair Value Disclosures - Level 3 Rollforwards (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 29, 2020	Feb. 28, 2019
Assets:
Total gains/losses (realized and unrealized)	$ (37,900)	$ (4,500)
Liabilities:
Total gains/losses (realized and unrealized)	(26,400)	(22,500)
Corporate equity securities
Assets:
Beginning Balance	58,301	51,040
Total gains/losses (realized and unrealized)	(8,195)	4,830
Purchases	2,792	1,410
Sales	(1,934)	(2,411)
Settlements	0	(66)
Issuances	0	0
Net transfers into/ (out of) Level 3	52,679	(37)
Ending Balance	103,643	54,766
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(8,206)	4,945
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Liabilities:
Beginning Balance	4,487	0
Total gains/losses (realized and unrealized)	291	(2)
Purchases	(513)	0
Sales	0	80
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	10	0
Ending Balance	4,275	78
For instruments still held, changes in unrealized gains/(losses) included in Earnings	65	2
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Corporate debt securities
Assets:
Beginning Balance	7,490	9,484
Total gains/losses (realized and unrealized)	1,269	466
Purchases	1,478	3,568
Sales	(503)	(3,233)
Settlements	(601)	(834)
Issuances	0	0
Net transfers into/ (out of) Level 3	15,957	1,479
Ending Balance	25,090	10,930
For instruments still held, changes in unrealized gains/(losses) included in Earnings	879	498
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Liabilities:
Beginning Balance	340	522
Total gains/losses (realized and unrealized)	(189)	(241)
Purchases	(13,832)	0
Sales	14,079	0
Settlements	369	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	449
Ending Balance	767	730
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(35)	241
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
CDOs and CLOs
Assets:
Beginning Balance	20,081	25,815
Total gains/losses (realized and unrealized)	(2,069)	(8,153)
Purchases	17,594	49,201
Sales	(17,833)	(32,759)
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	3,179	(1,538)
Ending Balance	20,952	32,566
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(1,823)	(3,814)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
RMBS
Assets:
Beginning Balance	17,740	19,603
Total gains/losses (realized and unrealized)	(280)	462
Purchases	0	975
Sales	0	0
Settlements	(3)	(27)
Issuances	0	0
Net transfers into/ (out of) Level 3	(487)	(50)
Ending Balance	16,970	20,963
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(250)	494
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
CMBS
Assets:
Beginning Balance	6,110	10,886
Total gains/losses (realized and unrealized)	(306)	136
Purchases	0	12
Sales	0	0
Settlements	(1,401)	(41)
Issuances	0	0
Net transfers into/ (out of) Level 3	(139)	1,827
Ending Balance	4,264	12,820
For instruments still held, changes in unrealized gains/(losses) included in Earnings	571	96
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Liabilities:
Beginning Balance	35	0
Total gains/losses (realized and unrealized)	0	70
Purchases	0	0
Sales	0	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	0
Ending Balance	35	70
For instruments still held, changes in unrealized gains/(losses) included in Earnings	0	(70)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Other ABS
Assets:
Beginning Balance	42,563	53,175
Total gains/losses (realized and unrealized)	(4,159)	(2,290)
Purchases	81,323	29,195
Sales	(72,032)	(30,060)
Settlements	(1,974)	(12,320)
Issuances	0	0
Net transfers into/ (out of) Level 3	(3,818)	(1,814)
Ending Balance	41,903	35,886
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(3,797)	(1,763)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Loans and other receivables
Assets:
Beginning Balance	64,240	46,985
Total gains/losses (realized and unrealized)	(3,781)	814
Purchases	12,940	40,061
Sales	(13,042)	(27,142)
Settlements	(7,087)	(1,990)
Issuances	0	0
Net transfers into/ (out of) Level 3	1,051	19,323
Ending Balance	54,321	78,051
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(5,109)	130
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Investments at fair value
Assets:
Beginning Balance	75,738	113,831
Total gains/losses (realized and unrealized)	(20,392)	(786)
Purchases	0	27,767
Sales	(76)	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	0
Ending Balance	55,270	140,812
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(20,392)	(786)
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Securities purchased under agreements to resell
Assets:
Beginning Balance	25,000
Total gains/losses (realized and unrealized)	0
Purchases	0
Sales	0
Settlements	(25,000)
Issuances	0
Net transfers into/ (out of) Level 3	0
Ending Balance	0
For instruments still held, changes in unrealized gains/(losses) included in Earnings	0
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0
Loans
Liabilities:
Beginning Balance	9,463	6,376
Total gains/losses (realized and unrealized)	1	(229)
Purchases	(9,872)	(1,411)
Sales	2,781	504
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	5,486	(1,820)
Ending Balance	7,859	3,420
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(1)	338
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Net derivatives
Liabilities:
Beginning Balance	77,168	21,614
Total gains/losses (realized and unrealized)	(17,528)	(5,348)
Purchases	(278)	(2,804)
Sales	5,627	3,084
Settlements	192	169
Issuances	0	0
Net transfers into/ (out of) Level 3	45,662	12,260
Ending Balance	110,843	28,975
For instruments still held, changes in unrealized gains/(losses) included in Earnings	17,460	3,333
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	0	0
Long-term debt
Liabilities:
Beginning Balance	480,069	200,745
Total gains/losses (realized and unrealized)	(9,016)	(16,701)
Purchases	0	0
Sales	0	0
Settlements	0	(5,665)
Issuances	128,475	92,016
Net transfers into/ (out of) Level 3	(56,065)
Ending Balance	543,463	283,139
For instruments still held, changes in unrealized gains/(losses) included in Earnings	(5,590)	4,045
For instruments still held, changes in unrealized gains/(losses) included in Other comprehensive income	$ 14,606	$ 12,656