Segment Reporting - Net Revenues, Expenses and Total Assets by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended									9 Months Ended	12 Months Ended
	Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	Feb. 28, 2013	Nov. 30, 2013	Nov. 30, 2015	Nov. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 513,087	$ 578,928	$ 791,554	$ 591,672	$ 524,809	$ 843,309	$ 722,992	$ 899,028
Segment assets	38,565,142				44,517,648						$ 38,565,142	$ 44,517,648
Capital Markets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment assets	37,806,100				44,002,600						37,806,100	44,002,600
Asset Management [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment assets	$ 759,000				$ 515,000						759,000	515,000
Successor [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues										$ 2,140,681	2,475,241	2,990,138
Expenses										1,873,018	2,361,014	2,687,117
Successor [Member] | Capital Markets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues										2,074,100	2,415,100	2,949,000
Expenses										1,840,400	2,325,200	2,652,000
Successor [Member] | Asset Management [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues										66,600	60,100	41,100
Expenses										$ 32,600	$ 35,800	$ 35,100
Predecessor [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									$ 818,544
Expenses									668,096
Predecessor [Member] | Capital Markets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									807,600
Expenses									660,600
Predecessor [Member] | Asset Management [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									10,900
Expenses									$ 7,500