Segment Reporting - Net Revenues, Expenses and Total Assets by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 741,769	$ 654,450	$ 719,408	$ 298,987	$ 513,087	$ 578,928	$ 791,554	$ 591,672	$ 2,414,614	$ 2,475,241	$ 2,990,138
Expenses									2,384,642	2,361,014	2,687,117
Segment assets	36,941,276				38,563,972				36,941,276	38,563,972
Capital Markets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									2,339,300	2,415,100	2,949,000
Expenses									2,321,500	2,325,200	2,652,000
Segment assets	35,931,800				37,805,000				35,931,800	37,805,000
Asset Management [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									75,300	60,100	41,100
Expenses									63,100	35,800	$ 35,100
Segment assets	$ 1,009,500				$ 759,000				$ 1,009,500	$ 759,000