Receivable and Allowance for Credit Losses - Loans Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 7,839,754	$ 7,641,593
Net deferred loan costs, fees and purchased premiums and discounts	34,783	35,971
Loans receivable	7,874,537	7,677,564
Real estate loans | One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,794,726	2,862,342
Real estate loans | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	1,409,187	1,239,207
Real estate loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,389,766	2,426,510
Real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	443,094	337,593
Commercial business loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	533,410	497,965
Consumer loans | Home equity loans and advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	266,770	274,551
Consumer loans | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	2,801	3,425
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	7,824,665	7,624,534
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	2,792,833	2,860,184
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	1,409,187	1,239,207
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	2,377,077	2,413,394
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	443,094	336,553
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Commercial business loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	533,041	497,469
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	266,632	274,302
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	2,801	3,425
Financial Asset Acquired with Credit Deterioration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	15,089	17,059
Financial Asset Acquired with Credit Deterioration | Real estate loans | One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	1,893	2,158
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	12,689	13,116
Financial Asset Acquired with Credit Deterioration | Real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	0	1,040
Financial Asset Acquired with Credit Deterioration | Commercial business loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	369	496
Financial Asset Acquired with Credit Deterioration | Consumer loans | Home equity loans and advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	138	249
Financial Asset Acquired with Credit Deterioration | Consumer loans | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total gross loans	$ 0	$ 0