Non-interest Expenses - Schedule of Components of Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Feb. 28, 2013	Nov. 30, 2013	Nov. 30, 2015	Nov. 30, 2014
Non-compensation expenses:
Goodwill impairment			$ 0	$ 54,000
Successor [Member]
Non-interest expenses:
Compensation and benefits		$ 1,213,908	1,467,131	1,698,530
Non-compensation expenses:
Floor brokerage and clearing fees		150,774	199,780	215,329
Technology and communications		193,683	313,044	268,212
Occupancy and equipment rental		86,701	101,138	107,767
Business development		63,115	105,963	106,984
Professional services		72,802	103,972	109,601
Bad debt provision		179	(396)	55,355
Goodwill impairment		0	0	54,000
Intangible assets amortization and impairment		20,784	13,487	20,569
Other		71,072	56,895	50,770
Total non-compensation expenses		659,110	893,883	988,587
Total non-interest expenses		$ 1,873,018	$ 2,361,014	$ 2,687,117
Predecessor [Member]
Non-interest expenses:
Compensation and benefits	$ 474,217
Non-compensation expenses:
Floor brokerage and clearing fees	46,155
Technology and communications	59,878
Occupancy and equipment rental	24,309
Business development	24,927
Professional services	24,135
Bad debt provision	1,945
Goodwill impairment	0
Intangible assets amortization and impairment	384
Other	12,146
Total non-compensation expenses	193,879
Total non-interest expenses	$ 668,096