ALLOWANCE FOR CREDIT LOSSES - Risk Category of Loans Based on Year of Origination (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	$ 1,095,410	$ 1,378,122
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,307,151	995,092
Financing Receivable Originated Two Years Before Latest Fiscal Year	864,969	804,013
Financing Receivable Originated Three Years Before Latest Fiscal Year	622,476	475,987
Financing Receivable Originated Four Years Before Latest Fiscal Year	426,774	338,502
Prior	709,307	487,340
Revolving Loans	486,801	315,703
Total loans		4,794,759
Total	5,512,888	4,803,799
Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,094,695	1,374,838
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,304,564	984,182
Financing Receivable Originated Two Years Before Latest Fiscal Year	845,406	784,679
Financing Receivable Originated Three Years Before Latest Fiscal Year	609,427	469,881
Financing Receivable Originated Four Years Before Latest Fiscal Year	422,351	330,898
Prior	687,718	472,098
Revolving Loans	477,747	303,741
Total loans		4,720,317
Total	5,441,908
Special Mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	715	2,058
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,473	4,665
Financing Receivable Originated Two Years Before Latest Fiscal Year	11,758	18,146
Financing Receivable Originated Three Years Before Latest Fiscal Year	11,986	1,565
Financing Receivable Originated Four Years Before Latest Fiscal Year		2,630
Prior	1,071	605
Revolving Loans	3,074	6,107
Total loans		35,776
Total	30,077
Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		1,226
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,114	6,245
Financing Receivable Originated Two Years Before Latest Fiscal Year	7,805	1,188
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,063	4,541
Financing Receivable Originated Four Years Before Latest Fiscal Year	4,423	4,974
Prior	20,518	14,637
Revolving Loans	5,980	5,855
Total loans		38,666
Total	40,903
Residential Properties
Financing Receivable Recorded Investment [Line Items]
Total	3,639,668
Residential Properties | Multifamily
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	664,743	774,701
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	886,772	638,237
Financing Receivable Originated Two Years Before Latest Fiscal Year	568,896	469,866
Financing Receivable Originated Three Years Before Latest Fiscal Year	368,554	218,470
Financing Receivable Originated Four Years Before Latest Fiscal Year	203,307	82,941
Prior	132,432	63,328
Total loans		2,247,543
Total	2,824,704
Residential Properties | Multifamily | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	664,743	774,701
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	886,772	638,237
Financing Receivable Originated Two Years Before Latest Fiscal Year	568,896	469,866
Financing Receivable Originated Three Years Before Latest Fiscal Year	368,554	218,470
Financing Receivable Originated Four Years Before Latest Fiscal Year	203,307	82,941
Prior	132,432	63,328
Total loans		2,247,543
Total	2,824,704
Residential Properties | Single Family
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	157,457	173,563
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	139,254	83,311
Financing Receivable Originated Two Years Before Latest Fiscal Year	64,441	110,560
Financing Receivable Originated Three Years Before Latest Fiscal Year	81,469	98,820
Financing Receivable Originated Four Years Before Latest Fiscal Year	74,656	107,568
Prior	270,670	203,826
Revolving Loans	27,017	28,365
Total loans		806,013
Total	814,964
Residential Properties | Single Family | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	157,457	173,563
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	139,254	83,311
Financing Receivable Originated Two Years Before Latest Fiscal Year	64,441	110,560
Financing Receivable Originated Three Years Before Latest Fiscal Year	81,469	95,888
Financing Receivable Originated Four Years Before Latest Fiscal Year	72,746	107,568
Prior	259,317	196,692
Revolving Loans	23,699	25,014
Total loans		792,596
Total	798,383
Residential Properties | Single Family | Special Mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Three Years Before Latest Fiscal Year		986
Revolving Loans	26
Total loans		986
Total	26
Residential Properties | Single Family | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Three Years Before Latest Fiscal Year		1,946
Financing Receivable Originated Four Years Before Latest Fiscal Year	1,910
Prior	11,353	7,134
Revolving Loans	3,292	3,351
Total loans		12,431
Total	16,555
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	18,446	46,260
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	39,848	107,104
Financing Receivable Originated Two Years Before Latest Fiscal Year	93,352	136,508
Financing Receivable Originated Three Years Before Latest Fiscal Year	110,995	131,456
Financing Receivable Originated Four Years Before Latest Fiscal Year	126,805	124,567
Prior	276,098	201,912
Total loans		747,807
Total	665,544
Commercial Real Estate | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	18,446	46,260
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	39,848	100,432
Financing Receivable Originated Two Years Before Latest Fiscal Year	76,796	120,230
Financing Receivable Originated Three Years Before Latest Fiscal Year	100,255	129,120
Financing Receivable Originated Four Years Before Latest Fiscal Year	124,522	119,719
Prior	268,611	194,533
Total loans		710,294
Total	628,478
Commercial Real Estate | Special Mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		743
Financing Receivable Originated Two Years Before Latest Fiscal Year	10,678	16,278
Financing Receivable Originated Three Years Before Latest Fiscal Year	10,740
Financing Receivable Originated Four Years Before Latest Fiscal Year		2,333
Prior	937	157
Total loans		19,511
Total	22,355
Commercial Real Estate | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		5,929
Financing Receivable Originated Two Years Before Latest Fiscal Year	5,878
Financing Receivable Originated Three Years Before Latest Fiscal Year		2,336
Financing Receivable Originated Four Years Before Latest Fiscal Year	2,283	2,515
Prior	6,550	7,222
Total loans		18,002
Total	14,711
Land and Construction
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		257
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	214	15,923
Financing Receivable Originated Two Years Before Latest Fiscal Year	16,623	27,792
Financing Receivable Originated Three Years Before Latest Fiscal Year	28,592	10,532
Financing Receivable Originated Four Years Before Latest Fiscal Year	10,538	706
Prior	598	622
Total loans		55,832
Total	56,565
Land and Construction | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		257
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	214	15,923
Financing Receivable Originated Two Years Before Latest Fiscal Year	16,623	27,792
Financing Receivable Originated Three Years Before Latest Fiscal Year	28,592	10,532
Financing Receivable Originated Four Years Before Latest Fiscal Year	10,538	706
Prior	598	622
Total loans		55,832
Total	56,565
Commercial and Industrial Loans
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	254,687	380,784
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	239,918	150,517
Financing Receivable Originated Two Years Before Latest Fiscal Year	121,657	57,966
Financing Receivable Originated Three Years Before Latest Fiscal Year	31,593	16,706
Financing Receivable Originated Four Years Before Latest Fiscal Year	11,468	15,936
Prior	29,417	17,552
Revolving Loans	452,708	279,215
Total loans		918,676
Total	1,141,448
Commercial and Industrial Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	253,972	377,500
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	237,331	146,279
Financing Receivable Originated Two Years Before Latest Fiscal Year	118,650	54,910
Financing Receivable Originated Three Years Before Latest Fiscal Year	29,284	15,868
Financing Receivable Originated Four Years Before Latest Fiscal Year	11,238	13,180
Prior	26,668	16,823
Revolving Loans	446,972	270,604
Total loans		895,164
Total	1,124,115
Commercial and Industrial Loans | Special Mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	715	2,058
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,473	3,922
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,080	1,868
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,246	579
Financing Receivable Originated Four Years Before Latest Fiscal Year		297
Prior	134	448
Revolving Loans	3,048	6,107
Total loans		15,279
Total	7,696
Commercial and Industrial Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		1,226
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,114	316
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,927	1,188
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,063	259
Financing Receivable Originated Four Years Before Latest Fiscal Year	230	2,459
Prior	2,615	281
Revolving Loans	2,688	2,504
Total loans		8,233
Total	9,637
Consumer Loans
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	77	2,557
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,145
Financing Receivable Originated Two Years Before Latest Fiscal Year		1,321
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,273	3
Financing Receivable Originated Four Years Before Latest Fiscal Year		6,784
Prior	92	100
Revolving Loans	7,076	8,123
Total loans		18,888
Total	9,663
Consumer Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	77	2,557
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,145
Financing Receivable Originated Two Years Before Latest Fiscal Year		1,321
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,273	3
Financing Receivable Originated Four Years Before Latest Fiscal Year		6,784
Prior	92	100
Revolving Loans	7,076	8,123
Total loans		$ 18,888
Total	$ 9,663