Financial Instruments (Details 2)	Nov. 30, 2011	Nov. 30, 2010
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	100.00%	100.00%
Financial Instruments Sold, Not Yet Purchased	100.00%	100.00%
Exchange closing prices [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	7.00%	9.00%
Financial Instruments Sold, Not Yet Purchased	19.00%	17.00%
Recently observed transaction prices [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	2.00%	5.00%
Financial Instruments Sold, Not Yet Purchased	1.00%	2.00%
Data providers/ pricing services [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	77.00%	65.00%
Financial Instruments Sold, Not Yet Purchased	75.00%	60.00%
Broker quotes [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	1.00%	12.00%
Financial Instruments Sold, Not Yet Purchased	0.00%	19.00%
Valuation techniques [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	13.00%	9.00%
Financial Instruments Sold, Not Yet Purchased	5.00%	2.00%