Loans Receivable and Allowance for Credit Losses - Credit Quality Indicators (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Jun. 30, 2025	Dec. 31, 2025
Total Loans
Total	$ 8,221,307			$ 8,253,818
Total gross charge-offs
Total	79	$ 991
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	184,280			1,005,660
2025/2024	998,751			526,871
2024/2023	536,951			709,362
2023/2022	703,165			1,692,333
2022/2021	1,659,920			1,442,790
Prior	3,743,529			2,469,245
Revolving Loans	279,293			325,533
Revolving Loans to Term Loans	105,260			71,582
Total	8,211,149			8,243,376
Total gross charge-offs
2026/2025	0		$ 296
2025/2024	17		647
2024/2023	5		984
2023/2022	21		2,267
2022/2021	14		838
Prior	22		2,192
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	79		7,224
Real estate loans \| One-to-four family
Total Loans
Total	2,544,838			2,559,519
Total gross charge-offs
Total	0	0
Real estate loans \| One-to-four family \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	31,265			93,590
2025/2024	94,578			105,510
2024/2023	104,889			150,438
2023/2022	147,282			708,500
2022/2021	698,355			688,327
Prior	1,467,219			811,887
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	2,543,588			2,558,252
Total gross charge-offs
2026/2025	0		0
2025/2024	0		0
2024/2023	0		0
2023/2022	0		0
2022/2021	0		0
Prior	0		0
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	0		0
Real estate loans \| One-to-four family \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	31,265			93,590
2025/2024	94,578			104,411
2024/2023	103,691			148,597
2023/2022	145,445			705,476
2022/2021	695,351			687,522
Prior	1,462,270			807,680
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	2,532,600			2,547,276
Real estate loans \| One-to-four family \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			0
2022/2021	0			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	0			0
Real estate loans \| One-to-four family \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			1,099
2024/2023	1,198			1,841
2023/2022	1,837			3,024
2022/2021	3,004			805
Prior	4,949			4,207
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	10,988			10,976
Real estate loans \| Multifamily
Total Loans
Total	1,669,232			1,677,613
Total gross charge-offs
Total	0	0
Real estate loans \| Multifamily \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	67,513			233,695
2025/2024	232,641			32,267
2024/2023	35,503			135,839
2023/2022	136,864			356,358
2022/2021	354,901			356,888
Prior	841,810			562,566
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	1,669,232			1,677,613
Total gross charge-offs
2026/2025	0		0
2025/2024	0		0
2024/2023	0		0
2023/2022	0		0
2022/2021	0		0
Prior	0		0
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	0		0
Real estate loans \| Multifamily \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	67,513			233,695
2025/2024	232,641			32,267
2024/2023	35,503			135,839
2023/2022	136,864			345,763
2022/2021	344,306			316,250
Prior	831,754			562,566
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	1,648,581			1,626,380
Real estate loans \| Multifamily \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			0
2022/2021	0			40,638
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	0			40,638
Real estate loans \| Multifamily \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			10,595
2022/2021	10,595			0
Prior	10,056			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	20,651			10,595
Real estate loans \| Commercial real estate
Total Loans
Total	2,480,804			2,521,151
Total gross charge-offs
Total	0	77
Real estate loans \| Commercial real estate \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	27,805			414,588
2025/2024	406,857			113,417
2024/2023	105,300			174,188
2023/2022	173,190			478,543
2022/2021	475,776			358,813
Prior	1,284,065			973,711
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	2,472,993			2,513,260
Total gross charge-offs
2026/2025	0		0
2025/2024	0		0
2024/2023	0		0
2023/2022	0		77
2022/2021	0		42
Prior	0		0
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	0		119
Real estate loans \| Commercial real estate \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	27,505			410,896
2025/2024	403,180			113,417
2024/2023	105,300			173,838
2023/2022	172,842			459,278
2022/2021	458,839			357,327
Prior	1,216,466			923,667
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	2,384,132			2,438,423
Real estate loans \| Commercial real estate \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			7,007
2022/2021	3,787			0
Prior	9,155			9,222
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	12,942			16,229
Real estate loans \| Commercial real estate \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	300			3,692
2025/2024	3,677			0
2024/2023	0			350
2023/2022	348			12,258
2022/2021	13,150			1,486
Prior	58,444			40,822
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	75,919			58,608
Real estate loans \| Construction
Total Loans
Total	520,753			469,438
Total gross charge-offs
Total	0	53
Real estate loans \| Construction \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	23,330			128,667
2025/2024	145,332			118,823
2024/2023	136,582			148,879
2023/2022	153,029			73,069
2022/2021	62,480			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	520,753			469,438
Total gross charge-offs
2026/2025	0		0
2025/2024	0		0
2024/2023	0		0
2023/2022	0		53
2022/2021	0		0
Prior	0		0
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	0		53
Real estate loans \| Construction \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	23,330			128,667
2025/2024	145,332			118,823
2024/2023	136,582			146,996
2023/2022	127,296			67,146
2022/2021	53,497			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	486,037			461,632
Real estate loans \| Construction \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	5,639			0
2022/2021	8,983			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	14,622			0
Real estate loans \| Construction \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			1,883
2023/2022	20,094			5,923
2022/2021	0			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	20,094			7,806
Commercial business loans \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	28,200			112,889
2025/2024	100,283			143,768
2024/2023	142,503			88,102
2023/2022	81,600			60,223
2022/2021	53,291			25,428
Prior	69,479			48,988
Revolving Loans	276,890			287,394
Revolving Loans to Term Loans	0			0
Total	752,246			766,792
Total gross charge-offs
2026/2025	0		295
2025/2024	0		634
2024/2023	0		926
2023/2022	0		2,097
2022/2021	0		753
Prior	0		2,182
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	0		6,887
Commercial business loans \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	26,250			111,377
2025/2024	98,775			142,106
2024/2023	140,645			86,839
2023/2022	80,826			58,117
2022/2021	51,289			24,846
Prior	60,334			41,814
Revolving Loans	261,166			266,563
Revolving Loans to Term Loans	0			0
Total	719,285			731,662
Commercial business loans \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			0
2022/2021	0			0
Prior	363			44
Revolving Loans	175			100
Revolving Loans to Term Loans	0			0
Total	538			144
Commercial business loans \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	1,950			1,512
2025/2024	1,508			1,662
2024/2023	1,858			1,263
2023/2022	774			2,106
2022/2021	2,002			582
Prior	8,782			7,130
Revolving Loans	15,549			20,731
Revolving Loans to Term Loans	0			0
Total	32,423			34,986
Home equity loans and advances \| Home equity loans and advances
Total Loans
Total	249,487			255,126
Total gross charge-offs
Total	0	0
Home equity loans and advances \| Home equity loans and advances \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	3,896			19,850
2025/2024	18,973			13,049
2024/2023	12,142			11,867
2023/2022	11,156			15,616
2022/2021	15,104			13,334
Prior	80,906			72,043
Revolving Loans	2,050			37,785
Revolving Loans to Term Loans	105,260			71,582
Total	249,487			255,126
Total gross charge-offs
2026/2025	0		0
2025/2024	0		0
2024/2023	0		0
2023/2022	0		0
2022/2021	0		0
Prior	0		0
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	0		0
Home equity loans and advances \| Home equity loans and advances \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	3,896			19,850
2025/2024	18,973			13,049
2024/2023	12,142			11,818
2023/2022	11,058			15,368
2022/2021	14,860			13,334
Prior	80,547			71,446
Revolving Loans	1,687			37,417
Revolving Loans to Term Loans	105,260			71,582
Total	248,423			253,864
Home equity loans and advances \| Home equity loans and advances \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			0
2022/2021	0			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	0			0
Home equity loans and advances \| Home equity loans and advances \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			49
2023/2022	98			248
2022/2021	244			0
Prior	359			597
Revolving Loans	363			368
Revolving Loans to Term Loans	0			0
Total	1,064			1,262
Home equity loans and advances \| Other consumer loans
Total Loans
Total	2,850			2,895
Total gross charge-offs
Total	79	$ 36
Home equity loans and advances \| Other consumer loans \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	2,271			2,381
2025/2024	87			37
2024/2023	32			49
2023/2022	44			24
2022/2021	13			0
Prior	50			50
Revolving Loans	353			354
Revolving Loans to Term Loans	0			0
Total	2,850			2,895
Total gross charge-offs
2026/2025	0		1
2025/2024	17		13
2024/2023	5		58
2023/2022	21		40
2022/2021	14		43
Prior	22		10
Revolving Loans	0		0
Revolving Loans to Term Loans	0		0
Total	79		$ 165
Home equity loans and advances \| Other consumer loans \| Pass \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	2,271			2,381
2025/2024	87			37
2024/2023	32			49
2023/2022	44			24
2022/2021	13			0
Prior	50			50
Revolving Loans	353			354
Revolving Loans to Term Loans	0			0
Total	2,850			2,895
Home equity loans and advances \| Other consumer loans \| Special mention \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			0
2022/2021	0			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	0			0
Home equity loans and advances \| Other consumer loans \| Substandard \| Financial Asset, Other than Financial Asset Acquired with Credit Deterioration
Total Loans
2026/2025	0			0
2025/2024	0			0
2024/2023	0			0
2023/2022	0			0
2022/2021	0			0
Prior	0			0
Revolving Loans	0			0
Revolving Loans to Term Loans	0			0
Total	$ 0			$ 0

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6