Variable Interest Entities - Assets and Liabilities of Consolidated VIEs Prior to Consolidation (Detail) (USD $)	Nov. 30, 2012	May 31, 2013 Successor [Member]	Feb. 28, 2013 Successor [Member]	May 31, 2013 Successor [Member] High Yield [Member]	May 31, 2013 Successor [Member] Securitization Vehicles [Member]	May 31, 2013 Successor [Member] Other [Member]	Feb. 28, 2013 Predecessor [Member]	Nov. 30, 2012 Predecessor [Member]	May 31, 2012 Predecessor [Member]	Nov. 30, 2011 Predecessor [Member]	Nov. 30, 2012 Predecessor [Member] High Yield [Member]	Nov. 30, 2012 Predecessor [Member] Securitization Vehicles [Member]	Nov. 30, 2012 Predecessor [Member] Other [Member]
Variable Interest Entity [Line Items]
Cash		$ 3,403,479,000	$ 3,017,958,000	$ 45,000,000		$ 200,000	$ 3,017,958,000	$ 2,692,595,000	$ 2,357,822,000	$ 2,393,797,000	$ 388,100,000		$ 200,000
Financial instruments owned		15,270,288,000			107,400,000	500,000		16,670,391,000			894,200,000	10,000,000	500,000
Securities borrowed		5,357,672,000						5,094,679,000			372,100,000
Securities purchased under agreement to resell		3,467,625,000			195,100,000			3,357,602,000				60,000,000
Receivable from brokers and dealers		3,281,400,000						1,424,027,000			264,500,000
Other		1,181,376,000						662,713,000			11,400,000
Total assets		38,928,266,000		45,000,000	302,500,000	700,000		36,293,541,000			1,930,300,000	70,000,000	700,000
Financial instruments sold, not yet purchased		6,771,793,000						7,455,463,000			526,100,000
Securities loaned		2,679,193,000						1,934,355,000			112,000,000
Payable to brokers and dealers		1,990,606,000						2,819,677,000			201,200,000
Mandatorily redeemable interests	348,051,000							348,051,000			1,076,000,000
Redemption payable				43,200,000
Other secured financings					302,500,000							70,000,000
Other				1,800,000		200,000					15,000,000		200,000
Total liabilities		$ 33,743,068,000		$ 45,000,000	$ 302,500,000	$ 200,000		$ 32,510,788,000			$ 1,930,300,000	$ 70,000,000	$ 200,000