LOANS HELD FOR INVESTMENT, NET - Allowance for Credit Losses Activity (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Allowance for loan losses [Roll Forward]
Beginning balance	$ 79,615,000	$ 98,200,000	$ 83,853,000	$ 41,461,000	$ 41,461,000
PCD Day 1				52,284,000
(Credit) provision for credit losses	366,000	(4,523,000)	(1,288,000)	8,126,000
Charge-offs	(645,000)	(1,033,000)	(3,283,000)	(5,308,000)
Recoveries	90,000	116,000	144,000	116,000
Ending balance	79,426,000	92,760,000	79,426,000	92,760,000	83,853,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	2,572,000		2,572,000		1,649,000
Non-accrual with Allowance	33,729,000		33,729,000		38,658,000
Reserve			19,369,000		19,409,000
Interest income on non-accrual loans held for investment
Interest income on non-accrual loans	0	0	0	0
Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				(3,919,000)	(3,919,000)
Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				37,542,000	37,542,000
Total real estate loans
Allowance for loan losses [Roll Forward]
Beginning balance	44,992,000	64,290,000	47,771,000	28,712,000	28,712,000
PCD Day 1				28,753,000
(Credit) provision for credit losses	(3,494,000)	(1,545,000)	(6,275,000)	7,514,000
Charge-offs		(583,000)		(841,000)
Recoveries	54,000	4,000	56,000	4,000
Ending balance	41,552,000	62,166,000	41,552,000	62,166,000	47,771,000
Total real estate loans | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				(1,976,000)	(1,976,000)
Total real estate loans | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				26,736,000	26,736,000
One-to-four family residential and cooperative/condominium apartment
Allowance for loan losses [Roll Forward]
Beginning balance	4,528,000	5,133,000	5,932,000	644,000	644,000
PCD Day 1				2,220,000
(Credit) provision for credit losses	(14,000)	394,000	(1,418,000)	1,629,000
Charge-offs		(5,000)		(19,000)
Ending balance	4,514,000	5,522,000	4,514,000	5,522,000	5,932,000
Amortized cost basis of loans on non-accrual status
Non-accrual with Allowance	3,128,000		3,128,000		7,623,000
Reserve			155,000		1,278,000
One-to-four family residential and cooperative/condominium apartment | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				1,048,000	1,048,000
One-to-four family residential and cooperative/condominium apartment | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				1,692,000	1,692,000
Multifamily residential and residential mixed-use
Allowance for loan losses [Roll Forward]
Beginning balance	7,061,000	10,421,000	7,816,000	17,016,000	17,016,000
PCD Day 1				3,292,000
(Credit) provision for credit losses	(58,000)	34,000	(815,000)	(1,363,000)
Charge-offs		(173,000)		(409,000)
Recoveries		3,000	2,000	3,000
Ending balance	7,003,000	10,285,000	7,003,000	10,285,000	7,816,000
Multifamily residential and residential mixed-use | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				(8,254,000)	(8,254,000)
Multifamily residential and residential mixed-use | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				8,762,000	8,762,000
Acquisition, development, and construction
Allowance for loan losses [Roll Forward]
Beginning balance	4,758,000	3,899,000	4,857,000	1,993,000	1,993,000
PCD Day 1				117,000
(Credit) provision for credit losses	(970,000)	1,259,000	(1,069,000)	2,667,000
Ending balance	3,788,000	5,158,000	3,788,000	5,158,000	4,857,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	657,000		657,000
Acquisition, development, and construction | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				381,000	381,000
Acquisition, development, and construction | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				2,374,000	2,374,000
Commercial real estate ("CRE")
Allowance for loan losses [Roll Forward]
Beginning balance	28,645,000	44,837,000	29,166,000	9,059,000	9,059,000
PCD Day 1				23,124,000
(Credit) provision for credit losses	(2,452,000)	(3,232,000)	(2,973,000)	4,581,000
Charge-offs		(405,000)		(413,000)
Recoveries	54,000	1,000	54,000	1,000
Ending balance	26,247,000	41,201,000	26,247,000	41,201,000	29,166,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	1,575,000		1,575,000		1,301,000
Non-accrual with Allowance	3,445,000		3,445,000		3,752,000
Reserve			1,360,000		797,000
Commercial real estate ("CRE") | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				4,849,000	4,849,000
Commercial real estate ("CRE") | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				13,908,000	13,908,000
Commercial and Industrial ("C&I") Loans
Allowance for loan losses [Roll Forward]
Beginning balance	34,263,000	33,378,000	35,331,000	12,737,000	12,737,000
PCD Day 1				23,374,000
(Credit) provision for credit losses	3,934,000	(2,947,000)	5,450,000	272,000
Charge-offs	(645,000)	(445,000)	(3,280,000)	(4,462,000)
Recoveries	36,000	109,000	87,000	109,000
Ending balance	37,588,000	30,095,000	37,588,000	30,095,000	35,331,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	340,000		340,000		348,000
Non-accrual with Allowance	27,025,000		27,025,000		26,918,000
Reserve			17,813,000		16,973,000
Commercial and Industrial ("C&I") Loans | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				(1,935,000)	(1,935,000)
Commercial and Industrial ("C&I") Loans | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				10,802,000	10,802,000
Other Loans
Allowance for loan losses [Roll Forward]
Beginning balance	360,000	532,000	751,000	12,000	12,000
PCD Day 1				157,000
(Credit) provision for credit losses	(74,000)	(31,000)	(463,000)	340,000
Charge-offs		(5,000)	(3,000)	(5,000)
Recoveries		3,000	1,000	3,000
Ending balance	286,000	$ 499,000	286,000	499,000	751,000
Amortized cost basis of loans on non-accrual status
Non-accrual with Allowance	$ 131,000		131,000		365,000
Reserve			$ 41,000		361,000
Other Loans | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Beginning balance				(8,000)	(8,000)
Other Loans | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Beginning balance				$ 4,000	$ 4,000