Covered Loans Acquired in AmTrust and Desert Hills Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 2,341,428	$ 2,428,622
Percent of Covered Loans	100.00%
One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	2,152,731
Percent of Covered Loans	91.90%
Other loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 188,697
Percent of Covered Loans	8.10%