Financial data pertaining to the different trusts (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Debt Disclosure [Line Items]
Debt Instrument Unamortized Discount	$ 404,196
Fixed Rate 500 Percent Until December 2013 And 900 Percent Thereafter Junior Subordinated Deferrable Interest Debentures With No Stated Maturity [Member]
Debt Disclosure [Line Items]
Junior subordinates debentures, carrying value	531,804	[1]	531,540	[1]
Junior subordinates debentures, aggregate liquidation amount	936,000		936,000
Debt Instrument Unamortized Discount	$ 404,196		$ 404,460

[1] The debentures are perpetual and may be redeemed by the Corporation at any time, subject to the consent of the Board of Governors of the Federal Reserve System. The discount on the debentures is being amortized over an estimated 30-year term that started in August 2009. The effective interest rate, including the discount accretion, was approximately 16% at March 31, 2014 and December 31, 2013.