Classification and Carrying Amount of Pledged Assets, in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total pledged assets	$ 16,972,439	$ 16,435,648	$ 16,855,278
Available-for-sale Securities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged Assets in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral	2,184,884	1,867,249	2,384,829
Held-to-maturity Securities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged Assets in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral	37,312	25,770	125,770
Loans Held-for-Sale
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged Assets in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral	1,539	2,862	3,069
Loans Held for Investment \| Covered Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged Assets in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral	4,347,453	4,787,002	4,893,577
Loans Held for Investment \| Non Covered Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged Assets in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral	10,326,448	9,695,200	9,392,857
Covered under Loss Sharing Agreements with FDIC
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged Assets in which the Secured Parties are Not Permitted to Sell or Repledge the Collateral	$ 74,803	$ 57,565	$ 55,176

The carrying amount, as of the date of the latest financial statement presented, of all assets that are pledged as collateral for the payment of the related debt obligation primarily arising from secured borrowings, repurchase agreements or other current or potential obligations, where the secured party does not have the right by contract or custom to sell or re-pledge the collateral and therefore are not reclassified and separately reported in the statement of financial position.

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The sum of the carrying amounts, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and for which the transferees are not permitted to sell or re-pledge them to an unrelated party.

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- Definition

The carrying amount as of the date of the latest financial statement presented of other debt securities classified as held to maturity which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

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- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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