LOANS RECEIVABLE - Credit-Rating Classification of Loans Receivable (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Jun. 30, 2025
Total loans
Originated current fiscal year	$ 80,227			$ 484,997
Originated fiscal year before current fiscal year	484,470			370,584
Originated two years before current fiscal year	369,274			881,531
Originated three years before current fiscal year	873,223			1,565,977
Originated four years before current fiscal year	1,513,934			825,017
Originated more than five years before current fiscal year	2,349,888			1,593,050
Revolving loans	96,585			93,383
Financing receivable, before allowance for credit loss, fee and loan in process	5,767,601			5,814,539
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		$ 0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	1,082		1,136
Revolving loans, writeoff	0		0
Total	1,082	$ 129	1,136
Commercial
Total loans
Financing receivable, before allowance for credit loss, fee and loan in process	3,961,636			4,012,678
Commercial \| Multi-family mortgage
Total loans
Originated current fiscal year	4,080			146,525
Originated fiscal year before current fiscal year	144,457			26,430
Originated two years before current fiscal year	26,366			591,647
Originated three years before current fiscal year	588,995			939,414
Originated four years before current fiscal year	894,119			231,737
Originated more than five years before current fiscal year	982,720			773,901
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	2,640,737			2,709,654
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	386		0
Revolving loans, writeoff	0		0
Total	386	0	0
Commercial \| Nonresidential mortgage
Total loans
Originated current fiscal year	17,782			132,407
Originated fiscal year before current fiscal year	131,885			81,426
Originated two years before current fiscal year	81,034			102,965
Originated three years before current fiscal year	101,774			190,781
Originated four years before current fiscal year	189,280			109,315
Originated more than five years before current fiscal year	467,214			369,613
Revolving loans	0			49
Financing receivable, before allowance for credit loss, fee and loan in process	988,969			986,556
Total current period gross charge-offs
Originated current fiscal year, writeoff	0
Originated fiscal year before current fiscal year, writeoff	0
Originated two years before current fiscal year, writeoff	0
Originated three years before current fiscal year, writeoff	0
Originated four years before current fiscal year, writeoff	0
Originated more than five years before current fiscal year, writeoff	5		830
Revolving loans, writeoff	0
Total	5	0	830
Commercial \| Commercial business
Total loans
Originated current fiscal year	16,091			23,816
Originated fiscal year before current fiscal year	17,180			9,755
Originated two years before current fiscal year	9,404			5,718
Originated three years before current fiscal year	5,165			21,958
Originated four years before current fiscal year	20,555			14,389
Originated more than five years before current fiscal year	21,370			9,343
Revolving loans	52,539			53,776
Financing receivable, before allowance for credit loss, fee and loan in process	142,304			138,755
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	636		295
Revolving loans, writeoff	0		0
Total	636	127	295
Commercial \| Construction
Total loans
Originated current fiscal year	1,226			41,990
Originated fiscal year before current fiscal year	52,851			90,212
Originated two years before current fiscal year	93,257			0
Originated three years before current fiscal year	0			979
Originated four years before current fiscal year	979			35,435
Originated more than five years before current fiscal year	35,578			3,362
Revolving loans	5,735			5,735
Financing receivable, before allowance for credit loss, fee and loan in process	189,626			177,713
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	0		0
Revolving loans, writeoff	0		0
Total	0	0	0
Residential
Total loans
Originated current fiscal year	40,790			138,854
Originated fiscal year before current fiscal year	137,282			160,632
Originated two years before current fiscal year	157,195			176,406
Originated three years before current fiscal year	172,662			411,028
Originated four years before current fiscal year	407,297			433,603
Originated more than five years before current fiscal year	834,136			428,063
Revolving loans	0			5
Financing receivable, before allowance for credit loss, fee and loan in process	1,749,362			1,748,591
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	45		2
Revolving loans, writeoff	0		0
Total	45	2	2
Consumer
Total loans
Financing receivable, before allowance for credit loss, fee and loan in process	56,603			53,270
Consumer \| Home equity loans
Total loans
Originated current fiscal year	0			800
Originated fiscal year before current fiscal year	451			1,786
Originated two years before current fiscal year	1,718			4,606
Originated three years before current fiscal year	4,440			1,731
Originated four years before current fiscal year	1,623			302
Originated more than five years before current fiscal year	7,687			7,792
Revolving loans	38,197			33,720
Financing receivable, before allowance for credit loss, fee and loan in process	54,116			50,737
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	10		2
Revolving loans, writeoff	0		0
Total	10	0	2
Consumer \| Other consumer
Total loans
Originated current fiscal year	258			605
Originated fiscal year before current fiscal year	364			343
Originated two years before current fiscal year	300			189
Originated three years before current fiscal year	187			86
Originated four years before current fiscal year	81			236
Originated more than five years before current fiscal year	1,183			976
Revolving loans	114			98
Financing receivable, before allowance for credit loss, fee and loan in process	2,487			2,533
Total current period gross charge-offs
Originated current fiscal year, writeoff	0		0
Originated fiscal year before current fiscal year, writeoff	0		0
Originated two years before current fiscal year, writeoff	0		0
Originated three years before current fiscal year, writeoff	0		0
Originated four years before current fiscal year, writeoff	0		0
Originated more than five years before current fiscal year, writeoff	0		7
Revolving loans, writeoff	0		0
Total	0	$ 0	$ 7
Pass \| Commercial \| Multi-family mortgage
Total loans
Originated current fiscal year	4,080			146,525
Originated fiscal year before current fiscal year	144,457			26,430
Originated two years before current fiscal year	26,366			591,647
Originated three years before current fiscal year	588,995			939,414
Originated four years before current fiscal year	892,595			219,907
Originated more than five years before current fiscal year	917,056			720,674
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	2,573,549			2,644,597
Pass \| Commercial \| Nonresidential mortgage
Total loans
Originated current fiscal year	17,782			132,407
Originated fiscal year before current fiscal year	131,885			81,426
Originated two years before current fiscal year	81,034			102,965
Originated three years before current fiscal year	101,774			190,781
Originated four years before current fiscal year	189,280			107,519
Originated more than five years before current fiscal year	448,811			352,364
Revolving loans	0			49
Financing receivable, before allowance for credit loss, fee and loan in process	970,566			967,511
Pass \| Commercial \| Commercial business
Total loans
Originated current fiscal year	16,091			23,729
Originated fiscal year before current fiscal year	17,094			9,355
Originated two years before current fiscal year	9,004			5,718
Originated three years before current fiscal year	5,165			20,915
Originated four years before current fiscal year	20,302			14,264
Originated more than five years before current fiscal year	20,653			7,608
Revolving loans	52,539			53,647
Financing receivable, before allowance for credit loss, fee and loan in process	140,848			135,236
Pass \| Commercial \| Construction
Total loans
Originated current fiscal year	1,226			41,990
Originated fiscal year before current fiscal year	52,851			85,712
Originated two years before current fiscal year	88,757			0
Originated three years before current fiscal year	0			979
Originated four years before current fiscal year	979			8,991
Originated more than five years before current fiscal year	12,329			3,362
Revolving loans	5,735			5,735
Financing receivable, before allowance for credit loss, fee and loan in process	161,877			146,769
Pass \| Residential
Total loans
Originated current fiscal year	40,790			138,854
Originated fiscal year before current fiscal year	137,282			160,333
Originated two years before current fiscal year	156,899			174,947
Originated three years before current fiscal year	171,218			410,255
Originated four years before current fiscal year	406,528			432,804
Originated more than five years before current fiscal year	824,226			417,105
Revolving loans	0			5
Financing receivable, before allowance for credit loss, fee and loan in process	1,736,943			1,734,303
Pass \| Consumer \| Home equity loans
Total loans
Originated current fiscal year	0			800
Originated fiscal year before current fiscal year	451			1,690
Originated two years before current fiscal year	1,625			4,606
Originated three years before current fiscal year	4,440			1,648
Originated four years before current fiscal year	1,540			302
Originated more than five years before current fiscal year	7,532			7,612
Revolving loans	38,035			33,553
Financing receivable, before allowance for credit loss, fee and loan in process	53,623			50,211
Pass \| Consumer \| Other consumer
Total loans
Originated current fiscal year	258			605
Originated fiscal year before current fiscal year	364			343
Originated two years before current fiscal year	300			189
Originated three years before current fiscal year	187			86
Originated four years before current fiscal year	81			236
Originated more than five years before current fiscal year	1,180			976
Revolving loans	27			26
Financing receivable, before allowance for credit loss, fee and loan in process	2,397			2,461
Special Mention \| Commercial \| Multi-family mortgage
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Special Mention \| Commercial \| Nonresidential mortgage
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			945
Originated more than five years before current fiscal year	6,589			6,187
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	6,589			7,132
Special Mention \| Commercial \| Commercial business
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			1,043
Originated four years before current fiscal year	253			125
Originated more than five years before current fiscal year	118			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	371			1,168
Special Mention \| Commercial \| Construction
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			5,950
Originated more than five years before current fiscal year	2,755			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	2,755			5,950
Special Mention \| Residential
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	303			687
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	303			687
Special Mention \| Consumer \| Home equity loans
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			96
Financing receivable, before allowance for credit loss, fee and loan in process	0			96
Special Mention \| Consumer \| Other consumer
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Substandard \| Commercial \| Multi-family mortgage
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	1,524			11,830
Originated more than five years before current fiscal year	65,664			53,227
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	67,188			65,057
Substandard \| Commercial \| Nonresidential mortgage
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			851
Originated more than five years before current fiscal year	11,814			11,062
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	11,814			11,913
Substandard \| Commercial \| Commercial business
Total loans
Originated current fiscal year	0			87
Originated fiscal year before current fiscal year	86			400
Originated two years before current fiscal year	400			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	599			1,735
Revolving loans	0			129
Financing receivable, before allowance for credit loss, fee and loan in process	1,085			2,351
Substandard \| Commercial \| Construction
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			4,500
Originated two years before current fiscal year	4,500			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			20,494
Originated more than five years before current fiscal year	20,494			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	24,994			24,994
Substandard \| Residential
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			299
Originated two years before current fiscal year	296			1,459
Originated three years before current fiscal year	1,444			773
Originated four years before current fiscal year	769			799
Originated more than five years before current fiscal year	9,607			10,271
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	12,116			13,601
Substandard \| Consumer \| Home equity loans
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			96
Originated two years before current fiscal year	93			0
Originated three years before current fiscal year	0			83
Originated four years before current fiscal year	83			0
Originated more than five years before current fiscal year	155			180
Revolving loans	162			71
Financing receivable, before allowance for credit loss, fee and loan in process	493			430
Substandard \| Consumer \| Other consumer
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Commercial \| Multi-family mortgage
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Commercial \| Nonresidential mortgage
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Commercial \| Commercial business
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Commercial \| Construction
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Residential
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Consumer \| Home equity loans
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	0			0
Revolving loans	0			0
Financing receivable, before allowance for credit loss, fee and loan in process	0			0
Doubtful \| Consumer \| Other consumer
Total loans
Originated current fiscal year	0			0
Originated fiscal year before current fiscal year	0			0
Originated two years before current fiscal year	0			0
Originated three years before current fiscal year	0			0
Originated four years before current fiscal year	0			0
Originated more than five years before current fiscal year	3			0
Revolving loans	87			72
Financing receivable, before allowance for credit loss, fee and loan in process	$ 90			$ 72

LOANS RECEIVABLE - Credit-Rating Classification of Loans Receivable (Details) - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

Sep. 30, 2025

Sep. 30, 2024

Dec. 31, 2024

Jun. 30, 2025

Total loans

Originated current fiscal year

$ 80,227

$ 484,997

Originated fiscal year before current fiscal year