Receivable and Allowance for Credit Losses - Rollforward of Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for loan losses:
Balance at beginning of period	$ 52,803	$ 62,689	$ 74,676
Initial allowance related to PCD loans	0	633	0
Provision for (reversal of) credit losses	4,787	5,969	(9,953)
Recoveries	1,000	593	1,530
Charge-offs	(3,494)	(638)	(3,564)
Balance at end of period	55,096	52,803	62,689
Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period	0	(16,443)	0
Balance at end of period		0	(16,443)
Real estate loans \| One-to-four family
Allowance for loan losses:
Balance at beginning of period	11,802	8,798	13,586
Initial allowance related to PCD loans		131
Provision for (reversal of) credit losses	1,783	5,225	(4,037)
Recoveries	17	338	22
Charge-offs	(585)	(382)	(773)
Balance at end of period	13,017	11,802	8,798
Real estate loans \| One-to-four family \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		(2,308)
Balance at end of period			(2,308)
Real estate loans \| Multifamily
Allowance for loan losses:
Balance at beginning of period	7,877	7,741	8,799
Initial allowance related to PCD loans		0
Provision for (reversal of) credit losses	865	2,166	(978)
Recoveries	0	0	216
Charge-offs	0	0	(296)
Balance at end of period	8,742	7,877	7,741
Real estate loans \| Multifamily \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		(2,030)
Balance at end of period			(2,030)
Real estate loans \| Commercial real estate
Allowance for loan losses:
Balance at beginning of period	18,111	16,114	21,882
Initial allowance related to PCD loans		474
Provision for (reversal of) credit losses	(2,225)	5,750	(6,376)
Recoveries	21	0	1,015
Charge-offs	(150)	0	(407)
Balance at end of period	15,757	18,111	16,114
Real estate loans \| Commercial real estate \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		(4,227)
Balance at end of period			(4,227)
Real estate loans \| Construction
Allowance for loan losses:
Balance at beginning of period	6,425	8,943	11,271
Initial allowance related to PCD loans		3
Provision for (reversal of) credit losses	1,333	(175)	(2,330)
Recoveries	0	0	2
Charge-offs	0	0	0
Balance at end of period	7,758	6,425	8,943
Real estate loans \| Construction \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		(2,346)
Balance at end of period			(2,346)
Commercial business loans
Allowance for loan losses:
Balance at beginning of period	6,897	20,214	17,384
Initial allowance related to PCD loans		19
Provision for (reversal of) credit losses	2,765	(8,052)	4,384
Recoveries	879	208	219
Charge-offs	(2,618)	(190)	(1,773)
Balance at end of period	7,923	6,897	20,214
Commercial business loans \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		(5,302)
Balance at end of period			(5,302)
Consumer loans \| Home equity loans and advances
Allowance for loan losses:
Balance at beginning of period	1,681	873	1,748
Initial allowance related to PCD loans		6
Provision for (reversal of) credit losses	160	1,019	(623)
Recoveries	77	45	56
Charge-offs	(26)	(33)	(308)
Balance at end of period	1,892	1,681	873
Consumer loans \| Home equity loans and advances \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		(229)
Balance at end of period			(229)
Consumer loans \| Other consumer loans
Allowance for loan losses:
Balance at beginning of period	10	6	6
Initial allowance related to PCD loans		0
Provision for (reversal of) credit losses	106	36	7
Recoveries	6	2	0
Charge-offs	(115)	(33)	(7)
Balance at end of period	$ 7	10	6
Consumer loans \| Other consumer loans \| Impact of adopting ASU 2016-13 (CECL) effective January 1, 2022
Allowance for loan losses:
Balance at beginning of period		$ (1)
Balance at end of period			$ (1)

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

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Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

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Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

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- Definition

Amount, excluding accrued interest, of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration. Excludes net investment in lease.

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