ALLOWANCE FOR CREDIT LOSSES - Risk Category of Loans Based on Year of Origination (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	$ 2,533,876	$ 1,973,024
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	2,120,873	1,224,189
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,338,436	666,713
Financing Receivable Originated Three Years Before Latest Fiscal Year	617,385	476,178
Financing Receivable Originated Four Years Before Latest Fiscal Year	472,243	326,563
Prior	888,215	1,515,612
Revolving Loans	967,813	724,449
Total loans		6,906,728
Total	8,938,841	6,906,728
Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	2,527,913	1,972,141
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	2,097,627	1,221,553
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,333,557	636,509
Financing Receivable Originated Three Years Before Latest Fiscal Year	588,408	475,196
Financing Receivable Originated Four Years Before Latest Fiscal Year	451,621	322,281
Prior	859,021	1,451,179
Revolving Loans	958,739	718,463
Total loans		6,797,322
Total	8,816,886
Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		883
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	13,715	1,101
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,487	25,505
Financing Receivable Originated Three Years Before Latest Fiscal Year	16,662
Financing Receivable Originated Four Years Before Latest Fiscal Year	20,104
Prior	7,990	32,453
Revolving Loans	7,051	2,816
Total loans		62,758
Total	67,009
Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	5,963
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	9,531	1,535
Financing Receivable Originated Two Years Before Latest Fiscal Year	3,392	4,699
Financing Receivable Originated Three Years Before Latest Fiscal Year	12,315	982
Financing Receivable Originated Four Years Before Latest Fiscal Year	518	4,282
Prior	21,204	31,980
Revolving Loans	2,023	3,170
Total loans		46,648
Total	54,946
Residential Properties
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		1,092,903
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		868,483
Financing Receivable Originated Two Years Before Latest Fiscal Year		419,523
Financing Receivable Originated Three Years Before Latest Fiscal Year		265,872
Financing Receivable Originated Four Years Before Latest Fiscal Year		141,433
Prior		108,529
Total loans		2,896,743
Total	4,928,374	3,832,495
Residential Properties | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		1,092,903
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		868,483
Financing Receivable Originated Two Years Before Latest Fiscal Year		418,346
Financing Receivable Originated Three Years Before Latest Fiscal Year		265,872
Financing Receivable Originated Four Years Before Latest Fiscal Year		141,433
Prior		108,529
Total loans		2,895,566
Residential Properties | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Two Years Before Latest Fiscal Year		1,177
Total loans		1,177
Multifamily
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,364,976
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,081,884
Financing Receivable Originated Two Years Before Latest Fiscal Year	817,796
Financing Receivable Originated Three Years Before Latest Fiscal Year	320,841
Financing Receivable Originated Four Years Before Latest Fiscal Year	179,739
Prior	202,422
Total	3,967,658
Multifamily | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	1,364,976
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,081,884
Financing Receivable Originated Two Years Before Latest Fiscal Year	817,796
Financing Receivable Originated Three Years Before Latest Fiscal Year	320,841
Financing Receivable Originated Four Years Before Latest Fiscal Year	179,739
Prior	202,422
Total	3,967,658
Single family
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	130,550	278,337
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	292,826	122,530
Financing Receivable Originated Two Years Before Latest Fiscal Year	100,637	52,995
Financing Receivable Originated Three Years Before Latest Fiscal Year	44,070	60,559
Financing Receivable Originated Four Years Before Latest Fiscal Year	52,904	59,047
Prior	269,355	287,046
Revolving Loans	70,374	75,238
Total loans		935,752
Total	960,716
Single family | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	130,550	278,337
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	292,826	122,530
Financing Receivable Originated Two Years Before Latest Fiscal Year	100,637	52,995
Financing Receivable Originated Three Years Before Latest Fiscal Year	44,070	60,559
Financing Receivable Originated Four Years Before Latest Fiscal Year	52,904	57,174
Prior	261,117	280,216
Revolving Loans	70,211	74,934
Total loans		926,745
Total	952,315
Single family | Special mention
Financing Receivable Recorded Investment [Line Items]
Revolving Loans	26	26
Total loans		26
Total	26
Single family | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Four Years Before Latest Fiscal Year		1,873
Prior	8,238	6,830
Revolving Loans	137	278
Total loans		8,981
Total	8,375
Commercial real estate
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	149,758	114,678
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	249,443	39,135
Financing Receivable Originated Two Years Before Latest Fiscal Year	143,639	85,855
Financing Receivable Originated Three Years Before Latest Fiscal Year	145,902	94,930
Financing Receivable Originated Four Years Before Latest Fiscal Year	177,375	117,831
Prior	370,048	857,146
Total loans		1,309,575
Total	1,236,165	1,309,575
Commercial real estate | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	143,795	114,678
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	226,528	39,135
Financing Receivable Originated Two Years Before Latest Fiscal Year	142,764	59,426
Financing Receivable Originated Three Years Before Latest Fiscal Year	119,380	94,930
Financing Receivable Originated Four Years Before Latest Fiscal Year	171,603	115,614
Prior	351,594	804,295
Total loans		1,228,078
Total	1,155,664
Commercial real estate | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	13,715
Financing Receivable Originated Two Years Before Latest Fiscal Year	46	23,495
Financing Receivable Originated Three Years Before Latest Fiscal Year	16,243
Financing Receivable Originated Four Years Before Latest Fiscal Year	5,772
Prior	7,990	30,389
Total loans		53,884
Total	43,766
Commercial real estate | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	5,963
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	9,200
Financing Receivable Originated Two Years Before Latest Fiscal Year	829	2,934
Financing Receivable Originated Three Years Before Latest Fiscal Year	10,279
Financing Receivable Originated Four Years Before Latest Fiscal Year		2,217
Prior	10,464	22,462
Total loans		27,613
Total	36,735
Land and Construction
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	32,273	14,738
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	54,823
Financing Receivable Originated Two Years Before Latest Fiscal Year	48,199	17,692
Financing Receivable Originated Three Years Before Latest Fiscal Year	12,272	31,952
Financing Receivable Originated Four Years Before Latest Fiscal Year	19,477	2,529
Prior	2,678	89,015
Total loans		155,926
Total	169,722	155,926
Land and Construction | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	32,273	14,738
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	54,823
Financing Receivable Originated Two Years Before Latest Fiscal Year	48,199	17,692
Financing Receivable Originated Three Years Before Latest Fiscal Year	12,272	31,952
Financing Receivable Originated Four Years Before Latest Fiscal Year	5,145	2,529
Prior	2,678	88,321
Total loans		155,232
Total	155,390
Land and Construction | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Four Years Before Latest Fiscal Year	14,332
Prior		694
Total loans		694
Total	14,332
Commercial and Industrial Loans
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	855,797	472,314
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	439,612	194,041
Financing Receivable Originated Two Years Before Latest Fiscal Year	228,161	90,648
Financing Receivable Originated Three Years Before Latest Fiscal Year	93,810	21,691
Financing Receivable Originated Four Years Before Latest Fiscal Year	42,464	5,723
Prior	43,638	171,259
Revolving Loans	890,244	642,189
Total loans		1,597,865
Total	2,593,726	1,597,865
Commercial and Industrial Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	855,797	471,431
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	439,281	191,405
Financing Receivable Originated Two Years Before Latest Fiscal Year	224,157	88,050
Financing Receivable Originated Three Years Before Latest Fiscal Year	91,489	20,709
Financing Receivable Originated Four Years Before Latest Fiscal Year	41,946	5,531
Prior	41,136	167,201
Revolving Loans	881,333	636,507
Total loans		1,580,834
Total	2,575,139
Commercial and Industrial Loans | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		883
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		1,101
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,441	833
Financing Receivable Originated Three Years Before Latest Fiscal Year	419
Prior		1,370
Revolving Loans	7,025	2,790
Total loans		6,977
Total	8,885
Commercial and Industrial Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	331	1,535
Financing Receivable Originated Two Years Before Latest Fiscal Year	2,563	1,765
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,902	982
Financing Receivable Originated Four Years Before Latest Fiscal Year	518	192
Prior	2,502	2,688
Revolving Loans	1,886	2,892
Total loans		10,054
Total	9,702
Consumer Loans
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	522	54
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	2,285
Financing Receivable Originated Two Years Before Latest Fiscal Year	4
Financing Receivable Originated Three Years Before Latest Fiscal Year	490	1,174
Financing Receivable Originated Four Years Before Latest Fiscal Year	284
Prior	74	2,617
Revolving Loans	7,195	7,022
Total loans		10,867
Total	10,854	10,867
Consumer Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	522	54
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	2,285
Financing Receivable Originated Two Years Before Latest Fiscal Year	4
Financing Receivable Originated Three Years Before Latest Fiscal Year	356	1,174
Financing Receivable Originated Four Years Before Latest Fiscal Year	284
Prior	74	2,617
Revolving Loans	7,195	7,022
Total loans		$ 10,867
Total	10,720
Consumer Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Three Years Before Latest Fiscal Year	134
Total	$ 134