Loans and Leases Receivable and Allowance for Loan and Lease Losses - Credit Quality Tables for Loans Receivable Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	$ 7,316,903	$ 7,138,498
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	5,442,307	6,181,911
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	111,157	126,180
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	139,744	110,080
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,597,188	700,664
Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	26,507	19,663
Multi-family
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,909,274	3,285,297
Multi-family | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,816,200	3,201,822
Multi-family | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	69,637	55,696
Multi-family | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	23,437	27,779
Multi-family | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Multi-family | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,889,980	1,373,800
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,841,074	1,306,466
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	26,285	30,551
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	22,621	36,783
Commercial and industrial | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial and industrial | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial real estate owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	552,007	577,477
Commercial real estate owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	536,777	562,639
Commercial real estate owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	8,286	9,730
Commercial real estate owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	6,944	5,108
Commercial real estate owner occupied | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial real estate owner occupied | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial real estate non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,223,529	1,125,106
Commercial real estate non-owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,129,838	1,054,493
Commercial real estate non-owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	6,949	30,203
Commercial real estate non-owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	86,742	40,410
Commercial real estate non-owner occupied | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial real estate non-owner occupied | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	118,418	56,491
Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	118,418	56,491
Construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	375,014	566,561
Residential real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Residential real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Residential real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Residential real estate | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	362,962	555,016
Residential real estate | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	12,052	11,545
Manufactured housing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	70,398	79,731
Manufactured housing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Manufactured housing | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Manufactured housing | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Manufactured housing | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	63,250	71,924
Manufactured housing | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	7,148	7,807
Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,178,283	74,035
Other consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Other consumer | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Other consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Other consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,170,976	73,724
Other consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	$ 7,307	$ 311