Fair Value Disclosures - Summary of Changes in Fair Value of Financial Liabilities Classified as Level 3 (Detail) (USD $)	3 Months Ended			6 Months Ended
	May 31, 2014	May 31, 2013	Feb. 28, 2013	May 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total gains/losses (realized and unrealized)	$ 8,500,000	$ 400,000	$ 2,700,000	$ 12,100,000
Corporate equity securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,015,000	38,000		38,000
Total gains/losses (realized and unrealized)	(977,000)
Purchases
Sales
Settlements
Issuances
Net transfers into/ (out of) Level 3
Ending Balance	38,000	38,000		38,000
Change in unrealized gains/(losses) relating to instruments still held	558,000
Corporate debt securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance
Total gains/losses (realized and unrealized)	(84,000)			(203,000)
Purchases	(4,082,000)			(28,319,000)
Sales	3,012,000			31,431,000
Settlements
Issuances
Net transfers into/ (out of) Level 3	3,934,000			(129,000)
Ending Balance	2,780,000			2,780,000
Change in unrealized gains/(losses) relating to instruments still held	84,000			203,000
Net derivatives [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	5,773,000	11,185,000		6,905,000
Total gains/losses (realized and unrealized)	9,485,000	(386,000)		11,591,000
Purchases	(2,150,000)			(179,000)
Sales	2,149,000			(21,000)
Settlements	25,000			318,000
Issuances
Net transfers into/ (out of) Level 3				(3,332,000)
Ending Balance	15,282,000	10,799,000		15,282,000
Change in unrealized gains/(losses) relating to instruments still held	(9,485,000)	386,000		(11,591,000)
Loans [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	10,260,000	7,398,000		22,462,000
Total gains/losses (realized and unrealized)	62,000			754,000
Purchases	(9,629,000)	(7,398,000)		(22,491,000)
Sales	18,995,000	15,212,000		27,908,000
Settlements	139,000			139,000
Issuances
Net transfers into/ (out of) Level 3	11,707,000			2,762,000
Ending Balance	31,534,000	15,212,000		31,534,000
Change in unrealized gains/(losses) relating to instruments still held	(57,000)			(57,000)
Other Secured Financings At Fair Value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	30,394,000			8,711,000
Total gains/losses (realized and unrealized)
Purchases	(992,000)
Sales
Settlements	(9,114,000)			(9,114,000)
Issuances				20,691,000
Net transfers into/ (out of) Level 3		2,294,000
Ending Balance	20,288,000	2,294,000		20,288,000
Change in unrealized gains/(losses) relating to instruments still held
Residential mortgage-backed securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		1,542,000
Total gains/losses (realized and unrealized)
Purchases		(1,542,000)
Ending Balance
Change in unrealized gains/(losses) relating to instruments still held
Predecessor [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Issuances			0
Predecessor [Member] | Corporate equity securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			38,000
Total gains/losses (realized and unrealized)
Purchases
Sales
Settlements
Net transfers into/ (out of) Level 3
Ending Balance			38,000
Change in unrealized gains/(losses) relating to instruments still held
Predecessor [Member] | Net derivatives [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			9,188,000
Total gains/losses (realized and unrealized)			2,648,000
Purchases
Sales
Settlements
Net transfers into/ (out of) Level 3			(651,000)
Ending Balance			11,185,000
Change in unrealized gains/(losses) relating to instruments still held			2,648,000
Predecessor [Member] | Loans [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance			1,711,000
Total gains/losses (realized and unrealized)
Purchases			(1,711,000)
Sales			7,398,000
Settlements
Net transfers into/ (out of) Level 3
Ending Balance			7,398,000
Change in unrealized gains/(losses) relating to instruments still held
Predecessor [Member] | Residential mortgage-backed securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance
Total gains/losses (realized and unrealized)			25,000
Purchases			(73,846,000)
Sales			75,363,000
Settlements
Net transfers into/ (out of) Level 3
Ending Balance			1,542,000
Change in unrealized gains/(losses) relating to instruments still held			$ (19,000)