Information Regarding Troubled Debt Restructurings (Detail) - Non-Covered Loans - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	$ 34,881	$ 45,556
Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	4,220	8,885
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings		368
One-to-four family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	1,022	1,066
Acquisition, development, and construction
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	8,297	8,652
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	21,342	26,585
Accruing
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	9,162	9,653
Accruing | Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings		824
Accruing | Acquisition, development, and construction
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	8,297	8,652
Accruing | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	865	177
Non-Accrual
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	25,719	35,903
Non-Accrual | Multi-Family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	4,220	8,061
Non-Accrual | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings		368
Non-Accrual | One-to-four family
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	1,022	1,066
Non-Accrual | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings	$ 20,477	$ 26,408