Financial Instruments (Details 2)	Aug. 31, 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	10.00%	9.00%
Financial Instruments Sold, Not Yet Purchased	16.00%	17.00%
Recently observed transaction prices [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	7.00%	5.00%
Financial Instruments Sold, Not Yet Purchased	2.00%	2.00%
Data providers/ pricing services [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	67.00%	65.00%
Financial Instruments Sold, Not Yet Purchased	74.00%	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	1.00%	19.00%
Valuation techniques [Member]
Financial instruments owned and Financial instruments sold, not yet purchased
Financial Instruments Owned	15.00%	9.00%
Financial Instruments Sold, Not Yet Purchased	7.00%	2.00%