Covered Loans Acquired in AmTrust and Desert Hills Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 4,008,287	$ 4,297,869
Percent of Covered Loans	100.00%
One- to Four-Family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	3,622,087
Percent of Covered Loans	90.04%
Other loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 386,200
Percent of Covered Loans	9.60%