Fair Value Disclosures - Level 3 Rollforwards (Detail) - USD ($) $ in Thousands	3 Months Ended
	Feb. 28, 2019	Feb. 28, 2018
Assets:
Total gains/losses (realized and unrealized)	$ (4,500)	$ 5,200
Liabilities:
Total gains/losses (realized and unrealized)	22,500	1,200
Corporate equity securities
Assets:
Beginning Balance	51,040	22,009
Total gains/losses (realized and unrealized)	4,830	11,684
Purchases	1,410	2,733
Sales	(2,411)	(1,381)
Settlements	(66)	(1,687)
Issuances	0	0
Net transfers into/ (out of) Level 3	(37)	2,054
Ending Balance	54,766	35,412
Change in unrealized gains/(losses) included in earnings for instruments still held	4,945	10,674
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Liabilities:
Beginning Balance	0	48
Total gains/losses (realized and unrealized)	(2)	13
Purchases	0	0
Sales	80	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	0
Ending Balance	78	61
Change in unrealized gains/(losses) included in earnings for to instruments still held	2	(13)
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0
Corporate debt securities
Assets:
Beginning Balance	9,484	26,036
Total gains/losses (realized and unrealized)	466	(9)
Purchases	3,568	928
Sales	(3,233)	(346)
Settlements	(834)	(2,049)
Issuances	0	0
Net transfers into/ (out of) Level 3	1,479	1,543
Ending Balance	10,930	26,103
Change in unrealized gains/(losses) included in earnings for instruments still held	498	(1,086)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Liabilities:
Beginning Balance	522	522
Total gains/losses (realized and unrealized)	(241)	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	449	0
Ending Balance	730	522
Change in unrealized gains/(losses) included in earnings for to instruments still held	241	0
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0
CDOs and CLOs
Assets:
Beginning Balance	25,815	30,004
Total gains/losses (realized and unrealized)	(8,153)	(3,782)
Purchases	49,201	43,796
Sales	(32,759)	(34,168)
Settlements	0	(3,838)
Issuances	0	0
Net transfers into/ (out of) Level 3	(1,538)	(5,579)
Ending Balance	32,566	26,433
Change in unrealized gains/(losses) included in earnings for instruments still held	(3,814)	(3,006)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
RMBS
Assets:
Beginning Balance	19,603	26,077
Total gains/losses (realized and unrealized)	462	(3,212)
Purchases	975	0
Sales	0	0
Settlements	(27)	(3)
Issuances	0	0
Net transfers into/ (out of) Level 3	(50)	(1,100)
Ending Balance	20,963	21,762
Change in unrealized gains/(losses) included in earnings for instruments still held	494	(2,366)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
CMBS
Assets:
Beginning Balance	10,886	12,419
Total gains/losses (realized and unrealized)	136	(231)
Purchases	12	1,260
Sales	0	(508)
Settlements	(41)	(1,285)
Issuances	0	0
Net transfers into/ (out of) Level 3	1,827	3,448
Ending Balance	12,820	15,103
Change in unrealized gains/(losses) included in earnings for instruments still held	96	(622)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Liabilities:
Beginning Balance	0	105
Total gains/losses (realized and unrealized)	70	(70)
Purchases	0	0
Sales	0	0
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	0
Ending Balance	70	35
Change in unrealized gains/(losses) included in earnings for to instruments still held	(70)	(35)
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0
Other ABS
Assets:
Beginning Balance	53,175	61,129
Total gains/losses (realized and unrealized)	(2,290)	(1,385)
Purchases	29,195	57,095
Sales	(30,060)	(53,459)
Settlements	(12,320)	(3,776)
Issuances	0	0
Net transfers into/ (out of) Level 3	(1,814)	(8,316)
Ending Balance	35,886	51,288
Change in unrealized gains/(losses) included in earnings for instruments still held	(1,763)	127
Change 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
Total gains/losses (realized and unrealized)	814	1,598
Purchases	40,061	15,635
Sales	(27,142)	(803)
Settlements	(1,990)	(9,730)
Issuances	0	0
Net transfers into/ (out of) Level 3	19,323	8,039
Ending Balance	78,051	62,043
Change in unrealized gains/(losses) included in earnings for instruments still held	130	(190)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Investments at fair value
Assets:
Beginning Balance	113,831	93,454
Total gains/losses (realized and unrealized)	(786)	499
Purchases	27,767	240
Sales	0	(16,624)
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	0	2,310
Ending Balance	140,812	79,879
Change in unrealized gains/(losses) included in earnings for instruments still held	(786)	(95)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0
Loans
Liabilities:
Beginning Balance	6,376	3,486
Total gains/losses (realized and unrealized)	(229)	6
Purchases	(1,411)	(25)
Sales	504	3,442
Settlements	0	0
Issuances	0	0
Net transfers into/ (out of) Level 3	(1,820)	3,414
Ending Balance	3,420	10,323
Change in unrealized gains/(losses) included in earnings for to instruments still held	338	(6)
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0
Net derivatives
Liabilities:
Beginning Balance	21,614	6,746
Total gains/losses (realized and unrealized)	(5,348)	(1,166)
Purchases	(2,804)	(6)
Sales	3,084	0
Settlements	169	1,012
Issuances	0	296
Net transfers into/ (out of) Level 3	12,260	0
Ending Balance	28,975	6,882
Change in unrealized gains/(losses) included in earnings for to instruments still held	3,333	$ (5,609)
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0
Long-term debt
Liabilities:
Beginning Balance	200,745
Total gains/losses (realized and unrealized)	(16,701)
Purchases	0
Sales	0
Settlements	(5,665)
Issuances	92,016
Net transfers into/ (out of) Level 3	12,744
Ending Balance	283,139
Change in unrealized gains/(losses) included in earnings for to instruments still held	4,045
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	$ 12,656