Fair Value Measurement of Assets and Liabilities - Schedule of Gains and Losses from Fair Value Changes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Gains And Losses From Fair Value Changes [Line Items]
Gains (Losses) on Change in Fair Value	$ (130)	$ 4,960	$ 1,419	$ 31,914
Trading Losses, Net [Member] | Trading Securities [Member]
Gains And Losses From Fair Value Changes [Line Items]
Gains (Losses) on Change in Fair Value	(35)	100	(78)	34
Trading Losses, Net [Member] | Junior Subordinated Debentures Issued to Capital Trusts [Member]
Gains And Losses From Fair Value Changes [Line Items]
Gains (Losses) on Change in Fair Value	0	2,131	0	(275)
Gains on Sales of Loans, Net [Member] | Loans Held for Sale [Member]
Gains And Losses From Fair Value Changes [Line Items]
Gains (Losses) on Change in Fair Value	$ (95)	$ 2,729	$ 1,497	$ 32,155