Loans Receivable and Allowance for Credit Losses - Loans Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 7,641,593	$ 6,335,722
Net deferred loan costs, fees and purchased premiums and discounts	35,971	24,879
Loans receivable	7,677,564	6,360,601
Real estate loans | One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,862,342	2,092,748
Real estate loans | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	1,239,207	1,041,108
Real estate loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,426,510	2,175,662
Real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	337,593	295,047
Commercial business loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	497,965	453,166
Consumer loans | Home equity loans and advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	274,551	276,563
Consumer loans | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	3,425	1,428
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	7,624,534	6,328,931
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,860,184	2,092,317
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	1,239,207	1,041,108
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,413,394	2,170,236
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	336,553	295,047
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	497,469	452,232
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	274,302	276,563
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	3,425	1,428
Financial Asset Acquired with Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	17,059	6,791
Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,158	431
Financial Asset Acquired with Credit Deterioration | Real estate loans | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	0	0
Financial Asset Acquired with Credit Deterioration | Real estate loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	13,116	5,426
Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	1,040	0
Financial Asset Acquired with Credit Deterioration | Commercial business loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	496	934
Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	249	0
Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 0	$ 0