Financial Instruments (Details 3) (USD $)	3 Months Ended							3 Months Ended														3 Months Ended
	Feb. 29, 2012	Feb. 28, 2011	Feb. 29, 2012 Corporate equity securities [Member]	Feb. 28, 2011 Corporate equity securities [Member]	Nov. 30, 2010 Corporate equity securities [Member]	Feb. 29, 2012 Corporate debt securities [Member]	Nov. 30, 2011 Corporate debt securities [Member]	Feb. 29, 2012 Net derivatives [Member]	Feb. 28, 2011 Net derivatives [Member]	Feb. 29, 2012 Loans [Member]	Feb. 28, 2011 Loans [Member]	Feb. 29, 2012 Corporate equity securities [Member]	Feb. 28, 2011 Corporate equity securities [Member]	Feb. 29, 2012 Corporate debt securities [Member]	Feb. 28, 2011 Corporate debt securities [Member]	Feb. 29, 2012 Collateralized Debt Obligations [Member]	Feb. 28, 2011 Collateralized Debt Obligations [Member]	Feb. 29, 2012 Municipal securities [Member]	Feb. 28, 2011 Municipal securities [Member]	Feb. 29, 2012 Sovereign obligations [Member]	Nov. 30, 2011 Sovereign obligations [Member]	Feb. 29, 2012 U.S. government agency residential mortgage-backed securities [Member]	Feb. 28, 2011 U.S. government agency residential mortgage-backed securities [Member]	Feb. 29, 2012 U.S. government agency commercial mortgage-backed securities [Member]	Feb. 28, 2011 U.S. government agency commercial mortgage-backed securities [Member]	Feb. 29, 2012 Other asset-backed securities [Member]	Feb. 28, 2011 Other asset-backed securities [Member]	Feb. 29, 2012 Loans and other receivables [Member]	Feb. 28, 2011 Loans and other receivables [Member]	Feb. 29, 2012 Investments at fair value [Member]	Feb. 28, 2011 Investments at fair value [Member]	Feb. 29, 2012 Investments in managed funds [Member]	Feb. 28, 2011 Investments in managed funds [Member]
Assets:
Beginning Balance												$ 13,489,000	$ 22,619,000	$ 48,140,000	$ 73,408,000	$ 47,988,000	$ 31,121,000	$ 6,904,000	$ 472,000	$ 140,000	$ 140,000	$ 149,965,000	$ 132,359,000	$ 52,407,000	$ 6,004,000	$ 3,284,000	$ 567,000	$ 97,291,000	$ 227,596,000	$ 78,326,000	$ 77,784,000	$ 70,740,000	$ 131,585,000
Total gains/ losses (realized and unrealized)	9,700,000	48,800,000										1,684,000	5,167,000	671,000	2,283,000	(796,000)	10,310,000	(71,000)	19,000			(6,492,000)	16,205,000	(1,655,000)	222,000	(104,000)	(215,000)	1,899,000	5,974,000	1,378,000	108,000	(6,212,000)	8,756,000
Purchases, sales, settlements, and issuances, net													6,772,000		(293,000)		60,299,000		308,000				(64,301,000)		2,804,000		617,000		(17,025,000)		(7,010,000)		(3,584,000)
Purchases												14,184,000		271,000								10,497,000						48,309,000		480,000		8,499,000
Sales														(22,300,000)		(14,063,000)		(740,000)				(44,282,000)		(3,593,000)		(197,000)		(21,733,000)		(1,797,000)		(12,000)
Settlements														(1,276,000)		(3,328,000)						(6,881,000)		(44,000)		(40,000)		(25,729,000)		(277,000)
Transfers into Level 3	109,900,000	26,800,000										900,000		8,600,000	106,000	42,800,000	1,216,000	500,000				32,500,000	12,886,000	1,500,000		4,700,000	11,050,000	18,400,000	1,574,000
Transfers out of Level 3	41,500,000	8,500,000											(1,277,000)	500,000	(520,000)			5,400,000				6,600,000	(40,000)	12,800,000	(2,729,000)	2,300,000	(567,000)	13,900,000	(368,000)		(3,048,000)
Net transfers into/ (out of) Level 3												912,000		8,100,000		42,775,000		(4,917,000)				25,944,000		(11,323,000)		2,446,000		4,412,000
Ending Balance												30,269,000	33,281,000	33,606,000	74,984,000	72,576,000	102,946,000	1,176,000	799,000	140,000	140,000	128,751,000	97,109,000	35,792,000	6,301,000	5,389,000	11,452,000	104,449,000	217,751,000	78,110,000	67,834,000	73,015,000	136,727,000
Change in unrealized gains/ (losses) relating to instruments												1,685,000	4,581,000	(737,000)	816,000	(1,488,000)	10,087,000	12,000	19,000			(5,995,000)	(2,745,000)	(1,419,000)	(824,000)	(76,000)	(469,000)	643,000	3,021,000	1,378,000	626,000	(6,212,000)	8,350,000
Liabilities:
Beginning Balance				38,000	38,000	74,000	74,000	9,285,000	2,346,000	10,157,000	47,228,000
Total gains/ losses (realized and unrealized)	1,500,000	2,600,000						1,512,000	2,611,000
Purchases, sales, settlements, and issuances, net											(29,452,000)
Purchases								(295,000)		(10,157,000)
Sales			11,511,000
Transfers into Level 3	0
Transfers out of Level 3	2,200,000	0
Net transfers into/ (out of) Level 3								2,192,000
Ending Balance			11,511,000	38,000	38,000	74,000	74,000	8,310,000	4,957,000		17,776,000
Change in unrealized gains/ (losses) relating to instruments								$ 2,736,000	$ 2,611,000