Fair Value Disclosures - Summary of Valuation Bases (Pricing Information) for Financial Instruments (Detail)	Feb. 28, 2013	Nov. 30, 2012
Financial Instruments Owned And Sold Not Yet Purchased Measured Using Different Valuation Basis [Line Items]
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 Sold Not Yet Purchased Measured Using Different Valuation Basis [Line Items]
Financial Instruments Owned	9.00%	11.00%
Financial Instruments Sold, Not Yet Purchased	17.00%	19.00%
Recently observed transaction prices [Member]
Financial Instruments Owned And Sold Not Yet Purchased Measured Using Different Valuation Basis [Line Items]
Financial Instruments Owned	4.00%	5.00%
Financial Instruments Sold, Not Yet Purchased	4.00%	6.00%
External pricing services [Member]
Financial Instruments Owned And Sold Not Yet Purchased Measured Using Different Valuation Basis [Line Items]
Financial Instruments Owned	72.00%	70.00%
Financial Instruments Sold, Not Yet Purchased	75.00%	71.00%
Broker quotes [Member]
Financial Instruments Owned And Sold Not Yet Purchased Measured Using Different Valuation Basis [Line Items]
Financial Instruments Owned	1.00%	1.00%
Financial Instruments Sold, Not Yet Purchased	0.00%	0.00%
Valuation techniques [Member]
Financial Instruments Owned And Sold Not Yet Purchased Measured Using Different Valuation Basis [Line Items]
Financial Instruments Owned	14.00%	13.00%
Financial Instruments Sold, Not Yet Purchased	4.00%	4.00%