Covered Loans Acquired in AmTrust and Desert Hills Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 3,032,172	$ 3,284,061
Percent of Covered Loans	100.00%
One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	2,753,300
Percent of Covered Loans	90.80%
Other loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 278,872
Percent of Covered Loans	9.20%