Fair Value Disclosures - Level 3 Rollforwards (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
Assets:
Total gains/losses (realized and unrealized)	$ 2,000	$ (17,900)	$ 2,700	$ (900)
Liabilities:
Total gains/losses (realized and unrealized)	14,100	25,800	42,800	27,600
Corporate equity securities
Assets:
Beginning Balance	54,766	35,412	51,040	22,009
Total gains/losses (realized and unrealized)	2,353	1,322	6,126	13,343
Purchases	221	1,485	785	5,383
Sales	(179)	(75)	(2,031)	(520)
Settlements	(551)	(110)	(720)	(1,779)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	2,697	4,867	4,107	4,465
Ending Balance	59,307	42,901	59,307	42,901
Change in unrealized gains/(losses) included in earnings for instruments still held	2,454	1,612	7,972	12,710
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
Liabilities:
Beginning Balance	78	61	0	48
Total gains/losses (realized and unrealized)	(74)	26	(76)	39
Purchases	(1,520)	0	(1,546)	0
Sales	1,737	0	1,843	0
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	0	0	0	0
Ending Balance	221	87	221	87
Change in unrealized gains/(losses) included in earnings for to instruments still held	0	(26)	0	(39)
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0		0
Corporate debt securities
Assets:
Beginning Balance	10,930	26,103	9,484	26,036
Total gains/losses (realized and unrealized)	(587)	923	(389)	434
Purchases	180	17,058	1,545	19,304
Sales	0	(13,481)	(2,130)	(15,704)
Settlements	(325)	0	(1,177)	(2,049)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(2,769)	(2,537)	96	45
Ending Balance	7,429	28,066	7,429	28,066
Change in unrealized gains/(losses) included in earnings for instruments still held	(588)	543	(334)	(1,048)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
Liabilities:
Beginning Balance	730	522	522	522
Total gains/losses (realized and unrealized)	(148)	0	(382)	0
Purchases	(7)	0	(73)	0
Sales	1	0	93	0
Settlements	22	0	22	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	71	0	487	0
Ending Balance	669	522	669	522
Change in unrealized gains/(losses) included in earnings for to instruments still held	90	0	305	0
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0		0
CDOs and CLOs
Assets:
Beginning Balance	32,566	26,433	25,815	30,004
Total gains/losses (realized and unrealized)	(1,793)	(2,350)	(2,790)	(2,961)
Purchases	0	251	4,782	568
Sales	0	(1,905)	0	(2,374)
Settlements	0	(431)	0	(3,765)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(14,578)	8,605	(11,612)	9,131
Ending Balance	16,195	30,603	16,195	30,603
Change in unrealized gains/(losses) included in earnings for instruments still held	(1,795)	(2,422)	(2,554)	(5,375)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
RMBS
Assets:
Beginning Balance	20,963	21,762	19,603	26,077
Total gains/losses (realized and unrealized)	(802)	(5,416)	(316)	(4,193)
Purchases	0	112	39	112
Sales	0	(13,113)	0	(10,959)
Settlements	(18)	(35)	(45)	(88)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(2,877)	345	(2,015)	(7,294)
Ending Balance	17,266	3,655	17,266	3,655
Change in unrealized gains/(losses) included in earnings for instruments still held	(759)	423	(271)	419
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
CMBS
Assets:
Beginning Balance	12,820	15,103	10,886	12,419
Total gains/losses (realized and unrealized)	(357)	(2,213)	(180)	(2,292)
Purchases	0	0	11	1,208
Sales	(331)	0	(331)	(487)
Settlements	(3,238)	(1,924)	(3,278)	(3,209)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	3,636	16,273	5,422	19,600
Ending Balance	12,530	27,239	12,530	27,239
Change in unrealized gains/(losses) included in earnings for instruments still held	(1,292)	(2,706)	(1,183)	(3,176)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
Liabilities:
Beginning Balance	70	35		105
Total gains/losses (realized and unrealized)	(70)	(35)		(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	0	0	0	0
Change in unrealized gains/(losses) included in earnings for to instruments still held	0	0		0
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0
Other ABS
Assets:
Beginning Balance	35,886	51,288	53,175	61,129
Total gains/losses (realized and unrealized)	3,070	(4,001)	(1,014)	(5,476)
Purchases	16,531	59,057	25,316	132,291
Sales	(8,868)	(62,905)	(13,247)	(124,787)
Settlements	(8,549)	(3,846)	(9,529)	(7,622)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	5,115	15,942	(11,516)	0
Ending Balance	43,185	55,535	43,185	55,535
Change in unrealized gains/(losses) included in earnings for instruments still held	3,563	(2,670)	(522)	(2,498)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
Loans and other receivables
Assets:
Beginning Balance	78,051	62,043	46,985	47,304
Total gains/losses (realized and unrealized)	(2,753)	(6,051)	2,434	(201)
Purchases	38,780	19,029	77,004	46,682
Sales	(13,898)	(16,237)	(33,549)	(25,456)
Settlements	(2,438)	(1,940)	(3,378)	(11,648)
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	742	7,192	8,988	7,355
Ending Balance	98,484	64,036	98,484	64,036
Change in unrealized gains/(losses) included in earnings for instruments still held	(1,277)	(5,185)	844	(1,756)
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
Investments at fair value
Assets:
Beginning Balance	140,812	79,879	113,831	93,454
Total gains/losses (realized and unrealized)	2,841	(82)	(1,162)	418
Purchases	0	2,001	31,343	2,240
Sales	0	(2,310)	0	(17,570)
Settlements	0	0	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	(39,820)	0	(40,179)	946
Ending Balance	103,833	79,488	103,833	79,488
Change in unrealized gains/(losses) included in earnings for instruments still held	2,841	(82)	(1,162)	(176)
Change 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		0
Total gains/losses (realized and unrealized)	0		0
Purchases	0		0
Sales	0		0
Settlements	0		0
Issuances	25,000		25,000
Net transfers into/ (out of) Level 3	0		0
Ending Balance	25,000		25,000
Change in unrealized gains/(losses) included in earnings for instruments still held	0		0
Change in unrealized gains/ (losses) included in other comprehensive income for instruments still held	0		0
Loans
Liabilities:
Beginning Balance	3,420	10,323	6,376	3,486
Total gains/losses (realized and unrealized)	(191)	(3,416)	(401)	1,226
Purchases	(1,678)	(10,543)	(3,946)	(5,100)
Sales	1,537	8,685	7,963	12,092
Settlements	0	(29)	0	0
Issuances	0	0	0	0
Net transfers into/ (out of) Level 3	6,340	7,861	(564)	1,177
Ending Balance	9,428	12,881	9,428	12,881
Change in unrealized gains/(losses) included in earnings for to instruments still held	364	3,231	579	106
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0		0
Net derivatives
Liabilities:
Beginning Balance	28,975	6,882	21,614	6,746
Total gains/losses (realized and unrealized)	(14,760)	(1,580)	(29,079)	(668)
Purchases	(25)	0	(2,829)	(6)
Sales	4,175	0	7,259	0
Settlements	1,974	569	2,031	(494)
Issuances	0	0	0	296
Net transfers into/ (out of) Level 3	27,110	3	48,453	0
Ending Balance	47,449	5,874	47,449	5,874
Change in unrealized gains/(losses) included in earnings for to instruments still held	7,565	(115)	19,607	535
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	0		0
Long-term debt
Liabilities:
Beginning Balance	283,139	0	200,745	0
Total gains/losses (realized and unrealized)	1,163	(20,838)	(12,854)	(28,082)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(5,585)	0	(11,250)	0
Issuances	39,385	23,362	101,872	81,284
Net transfers into/ (out of) Level 3	(81,540)		(41,951)
Ending Balance	236,562	160,626	236,562	160,626
Change in unrealized gains/(losses) included in earnings for to instruments still held	(813)	$ 20,838	3,827	$ 20,082
Change in unrealized gains/(losses) included in other comprehensive income for instruments still held	$ (350)		$ 9,027