Information Regarding Troubled Debt Restructurings (Detail) - Non-Covered Loans - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	$ 41,700	$ 45,556
Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	5,990	8,885
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	356	368
One-to-four family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	1,043	1,066
Acquisition, Development and Construction
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	9,552	8,652
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	24,759	26,585
Accruing
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	10,368	9,653
Accruing | Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	816	824
Accruing | Acquisition, Development and Construction
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	9,552	8,652
Accruing | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings		177
Non-Accrual
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	31,332	35,903
Non-Accrual | Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	5,174	8,061
Non-Accrual | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	356	368
Non-Accrual | One-to-four family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	1,043	1,066
Non-Accrual | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	$ 24,759	$ 26,408