LOANS HELD FOR INVESTMENT, NET - Allowance for Credit Losses Activity (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	$ 79,426,000	$ 92,760,000	$ 83,853,000	$ 41,461,000
PCD Day 1				52,284,000
Provision (credit) for credit losses	6,440,000	(7,314,000)	5,152,000	812,000
Charge-offs	(5,511,000)	(4,276,000)	(8,794,000)	(9,584,000)
Recoveries	1,580,000	85,000	1,724,000	201,000
Allowance for credit losses, Ending balance	81,935,000	81,255,000	81,935,000	81,255,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	4,877,000		4,877,000		$ 1,649,000
Non-accrual with Allowance	36,204,000		36,204,000		38,658,000
Reserve	20,153,000		20,153,000		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]
Allowance for credit losses, Beginning balance				(3,919,000)
Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				37,542,000
Total real estate loans
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	41,552,000	62,166,000	47,771,000	28,712,000
PCD Day 1				28,753,000
Provision (credit) for credit losses	3,730,000	(10,203,000)	(2,545,000)	(2,689,000)
Charge-offs		(3,011,000)		(3,852,000)
Recoveries		81,000	56,000	85,000
Allowance for credit losses, Ending balance	45,282,000	49,033,000	45,282,000	49,033,000
Total real estate loans | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				(1,976,000)
Total real estate loans | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				26,736,000
One-to-four family residential and cooperative/condominium apartment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	4,514,000	5,522,000	5,932,000	644,000
PCD Day 1				2,220,000
Provision (credit) for credit losses	544,000	583,000	(874,000)	2,212,000
Charge-offs		(1,000)		(20,000)
Allowance for credit losses, Ending balance	5,058,000	6,104,000	5,058,000	6,104,000
Amortized cost basis of loans on non-accrual status
Non-accrual with Allowance	3,219,000		3,219,000		7,623,000
Reserve	179,000		179,000		1,278,000
One-to-four family residential and cooperative/condominium apartment | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				1,048,000
One-to-four family residential and cooperative/condominium apartment | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				1,692,000
Multifamily residential and residential mixed-use
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	7,003,000	10,285,000	7,816,000	17,016,000
PCD Day 1				3,292,000
Provision (credit) for credit losses	1,051,000	(1,998,000)	236,000	(3,361,000)
Charge-offs		(58,000)		(467,000)
Recoveries		78,000	2,000	81,000
Allowance for credit losses, Ending balance	8,054,000	8,307,000	8,054,000	8,307,000
Multifamily residential and residential mixed-use | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				(8,254,000)
Multifamily residential and residential mixed-use | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				8,762,000
Acquisition, development, and construction
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	3,788,000	5,158,000	4,857,000	1,993,000
PCD Day 1				117,000
Provision (credit) for credit losses	(169,000)	(139,000)	(1,238,000)	2,528,000
Allowance for credit losses, Ending balance	3,619,000	5,019,000	3,619,000	5,019,000
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]
Allowance for credit losses, Beginning balance				381,000
Acquisition, development, and construction | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				2,374,000
Commercial real estate ("CRE")
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	26,247,000	41,201,000	29,166,000	9,059,000
PCD Day 1				23,124,000
Provision (credit) for credit losses	2,304,000	(8,649,000)	(669,000)	(4,068,000)
Charge-offs		(2,952,000)		(3,365,000)
Recoveries		3,000	54,000	4,000
Allowance for credit losses, Ending balance	28,551,000	29,603,000	28,551,000	29,603,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	3,848,000		3,848,000		1,301,000
Non-accrual with Allowance	3,825,000		3,825,000		3,752,000
Reserve	1,470,000		1,470,000		797,000
Commercial real estate ("CRE") | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				4,849,000
Commercial real estate ("CRE") | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				13,908,000
Commercial and Industrial ("C&I") Loans
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	37,588,000	30,095,000	35,331,000	12,737,000
PCD Day 1				23,374,000
Provision (credit) for credit losses	2,742,000	1,943,000	8,192,000	2,215,000
Charge-offs	(5,462,000)	(497,000)	(8,742,000)	(4,959,000)
Recoveries	1,580,000	4,000	1,667,000	113,000
Allowance for credit losses, Ending balance	36,448,000	31,545,000	36,448,000	31,545,000
Amortized cost basis of loans on non-accrual status
Non-accrual with No Allowance	372,000		372,000		348,000
Non-accrual with Allowance	29,160,000		29,160,000		26,918,000
Reserve	18,504,000		18,504,000		16,973,000
Commercial and Industrial ("C&I") Loans | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				(1,935,000)
Commercial and Industrial ("C&I") Loans | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				10,802,000
Other Loans
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance	286,000	499,000	751,000	12,000
PCD Day 1				157,000
Provision (credit) for credit losses	(32,000)	946,000	(495,000)	1,286,000
Charge-offs	(49,000)	(768,000)	(52,000)	(773,000)
Recoveries			1,000	3,000
Allowance for credit losses, Ending balance	$ 205,000	$ 677,000	$ 205,000	677,000
Amortized cost basis of loans on non-accrual status
Non-accrual with Allowance					365,000
Reserve					$ 361,000
Other Loans | Cumulative Effect, CECL Adoption, Adjustment
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				(8,000)
Other Loans | Cumulative Effect, CECL Adoption, Adjusted Balance
Allowance for loan losses [Roll Forward]
Allowance for credit losses, Beginning balance				$ 4,000