Goodwill and Other Intangible Assets (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Feb. 29, 2012	Nov. 30, 2011	Nov. 30, 2010
Intangible Assets
Gross cost	$ 23,541	$ 23,161
Accumulated amortization	(3,714)	(3,145)
Net carrying amount	19,827	20,016
Exchange and clearing organization membership interests and registrations [Member]
Intangible Assets
Gross cost	11,219	11,219
Accumulated amortization
Net carrying amount	11,219	11,219
Customer Relationships [Member]
Intangible Assets
Gross cost	10,542	10,542
Accumulated amortization	(3,128)	(2,776)
Net carrying amount	7,414	7,766
Weighted average remaining lives (years)	6.7	6.9
Trade names (intangible assets) [Member]
Intangible Assets
Gross cost	1,680	1,300
Accumulated amortization	(578)	(361)
Net carrying amount	1,102	939
Weighted average remaining lives (years)	1.8	1.1
Other Intangible Assets [Member]
Intangible Assets
Gross cost	100	100
Accumulated amortization	(8)	(8)
Net carrying amount	$ 92	$ 92
Weighted average remaining lives (years)	13.5	13.8