Information Regarding Troubled Debt Restructurings (Detail) (Non-Covered Loans, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	$ 33,692	$ 45,763
Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	13,705	25,576
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	17,876	18,078
One-to-four family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	259	260
Acquisition, Development and Construction
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	654	654
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	1,198	1,195
Accruing
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	15,898	15,836
Accruing | Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	7,664	7,697
Accruing | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	8,234	8,139
Non-Accrual
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	17,794	29,927
Non-Accrual | Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	6,041	17,879
Non-Accrual | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	9,642	9,939
Non-Accrual | One-to-four family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	259	260
Non-Accrual | Acquisition, Development and Construction
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	654	654
Non-Accrual | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	$ 1,198	$ 1,195