Financial Instruments (Details 3) (USD $) In Thousands	3 Months Ended		8 Months Ended	9 Months Ended
	Aug. 31, 2011	Aug. 31, 2010	Aug. 31, 2010	Aug. 31, 2011
Assets:
Total gains/ losses (realized and unrealized)	$ 19,200	$ 9,400	$ 57,900	$ 17,400
Transfers into Level 3	120,400	30,400	35,000	54,700
Transfers out of Level 3	152,400	4,200	183,500	81,800
Liabilities:
Total gains/ losses (realized and unrealized)	500	800	6,100	900
Transfers into Level 3	0		100	0
Transfers out of Level 3	10		113,300	0
Corporate equity securities [Member]
Assets:
Beginning Balance	18,230	21,918	43,042	22,619
Total gains/ losses (realized and unrealized)	1,720	1,327	(20,125)	2,905
Purchases, sales, settlements, and issuances, net	2,631	2,751	5,467	(3,040)
Transfers into Level 3	861		143	816
Transfers out of Level 3	(12,030)	(417)	(2,948)	(11,888)
Ending Balance	11,412	25,579	25,579	11,412
Change in unrealized gains/ (losses) relating to instruments	(154)	(789)	(22,524)	(422)
Corporate equity securities [Member]
Liabilities:
Beginning Balance	38	38	0	38
Total gains/ losses (realized and unrealized)	21			21
Purchases, sales, settlements, and issuances, net	0			0
Transfers into Level 3	0	58	96	0
Transfers out of Level 3	0			0
Ending Balance	59	96	96	59
Change in unrealized gains/ (losses) relating to instruments	20			20
Corporate debt securities [Member]
Assets:
Beginning Balance	39,688	100,275	116,648	73,408
Total gains/ losses (realized and unrealized)	(4,069)	(714)	(1,056)	(487)
Purchases, sales, settlements, and issuances, net	6,230	3,149	(1,084)	(22,533)
Transfers into Level 3	14,425	54	75	6,304
Transfers out of Level 3	(1,044)	(1,480)	(13,299)	(1,462)
Ending Balance	55,230	101,284	101,284	55,230
Change in unrealized gains/ (losses) relating to instruments	(7,349)	(813)	1,060	(5,906)
Corporate debt securities [Member]
Liabilities:
Beginning Balance		14,365	0
Total gains/ losses (realized and unrealized)		(1,275)	(2,210)
Purchases, sales, settlements, and issuances, net		(13,090)	2,210
Collateralized Debt Obligations [Member]
Assets:
Beginning Balance	84,046	21,957	9,570	31,121
Total gains/ losses (realized and unrealized)	(3,417)	(495)	5,397	10,423
Purchases, sales, settlements, and issuances, net	9,325	352	4,067	54,351
Transfers into Level 3	19,029	4,492	7,272	779
Transfers out of Level 3	(12,319)			(10)
Ending Balance	96,664	26,306	26,306	96,664
Change in unrealized gains/ (losses) relating to instruments	(5,413)	(615)	4,840	9,632
U.S. issued municipal securities [Member]
Assets:
Beginning Balance	858	436	420	472
Total gains/ losses (realized and unrealized)	11	(7)	9	89
Purchases, sales, settlements, and issuances, net	(183)			125
Ending Balance	686	429	429	686
Change in unrealized gains/ (losses) relating to instruments	1	(7)	9	78
Sovereign obligations [Member]
Assets:
Beginning Balance			196
Purchases, sales, settlements, and issuances, net	128			128
Transfers out of Level 3			(196)
Ending Balance	128			128
Residential mortgage-backed securities [Member]
Assets:
Beginning Balance	206,721	148,833	136,496	132,359
Total gains/ losses (realized and unrealized)	(12,527)	5,914	21,857	(8,354)
Purchases, sales, settlements, and issuances, net	15,276	(8,770)	(5,893)	64,906
Transfers into Level 3	41,510	23,143	23,435	29,901
Transfers out of Level 3	(79,461)	(1,281)	(8,056)	(47,293)
Ending Balance	171,519	167,839	167,839	171,519
Change in unrealized gains/ (losses) relating to instruments	(12,917)	404	6,888	25,284
Commercial mortgage-backed securities [Member]
Assets:
Beginning Balance	33,516	1,000	3,215	6,004
Total gains/ losses (realized and unrealized)	(3,652)		11	1,625
Purchases, sales, settlements, and issuances, net	(292)	50	(1,241)	25,574
Transfers into Level 3	17,364			6,992
Transfers out of Level 3	(6,741)	(1,000)	(1,935)
Ending Balance	40,195	50	50	40,195
Change in unrealized gains/ (losses) relating to instruments	(3,690)			112
Other asset-backed securities [Member]
Assets:
Beginning Balance	9,352	369	110	567
Total gains/ losses (realized and unrealized)	(329)			(604)
Purchases, sales, settlements, and issuances, net	2,773	(369)	(110)	3,156
Transfers into Level 3	99			926
Transfers out of Level 3	(8,417)			(567)
Ending Balance	3,478			3,478
Change in unrealized gains/ (losses) relating to instruments	(329)			(604)
Loans and other receivables [Member]
Assets:
Beginning Balance	261,056	145,181	506,542	227,596
Total gains/ losses (realized and unrealized)	710	(4,735)	38,029	2,476
Purchases, sales, settlements, and issuances, net	92,362	(55,105)	(302,151)	(57,473)
Transfers into Level 3	27,077			9,006
Transfers out of Level 3	(32,318)		(157,079)	(17,442)
Ending Balance	164,163	85,341	85,341	164,163
Change in unrealized gains/ (losses) relating to instruments	(116)	(4,139)	14,960	(1,452)
Investments at fair value [Member]
Assets:
Beginning Balance	71,008	72,297	65,564	77,784
Total gains/ losses (realized and unrealized)	2,397	8,060	13,744	9,326
Purchases, sales, settlements, and issuances, net	19,045	(3,724)	(3,991)	8,421
Transfers into Level 3	11	2,723	4,039	0
Transfers out of Level 3	(33)			(3,103)
Ending Balance	92,428	79,356	79,356	92,428
Change in unrealized gains/ (losses) relating to instruments	(938)	9,145	11,029	6,495
Net derivatives [Member]
Liabilities:
Beginning Balance	2,739	1,271	6,835	2,346
Total gains/ losses (realized and unrealized)	696	523	(3,585)	1,100
Purchases, sales, settlements, and issuances, net	0			0
Transfers into Level 3	0			0
Transfers out of Level 3	11	(500)	(1,956)	0
Ending Balance	3,446	1,294	1,294	3,446
Change in unrealized gains/ (losses) relating to instruments	687	523	(3,585)	1,200
Loans [Member]
Liabilities:
Beginning Balance	6,398	68,242	352,420	47,228
Total gains/ losses (realized and unrealized)	(230)		(344)	(230)
Purchases, sales, settlements, and issuances, net	5,290	(42,130)	(214,670)	(35,540)
Transfers into Level 3	0			0
Transfers out of Level 3	0		(111,294)	0
Ending Balance	11,458	26,112	26,112	11,458
Change in unrealized gains/ (losses) relating to instruments	$ (230)			$ (230)