Commitments, Contingencies and Guarantees (Details 3) (Index Credit Default Swaps [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Feb. 29, 2012
Derivative contracts- credit related:
External Credit Ratings For Derivative Contract Credit	$ 399.7
A Rating [Member]
Derivative contracts- credit related:
External Credit Ratings For Derivative Contract Credit	315.0
AAA - rated securities [Member]
Derivative contracts- credit related:
External Credit Ratings For Derivative Contract Credit	19.6
AA/AA [Member]
Derivative contracts- credit related:
External Credit Ratings For Derivative Contract Credit	10.0
External Credit Rating, Non Investment Grade [Member]
Derivative contracts- credit related:
External Credit Ratings For Derivative Contract Credit	14.8
Unrated [Member]
Derivative contracts- credit related:
External Credit Ratings For Derivative Contract Credit	$ 40.3