ALLOWANCE FOR CREDIT LOSSES - Risk Category of Loans Based on Year of Origination (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	$ 95,747	$ 4,120,524
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	4,108,404	2,444,776
Financing Receivable Originated Two Years Before Latest Fiscal Year	2,390,420	1,272,071
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,229,807	524,695
Financing Receivable Originated Four Years Before Latest Fiscal Year	487,530	409,795
Prior	1,093,689	733,966
Revolving Loans	1,264,206	1,220,366
Total	10,669,803	10,726,193
Financing Receivable Recorded Investment
Gross charge-offs Originated In Fiscal Year Before Latest Fiscal Year	375
Gross charge-offs Originated Two Years Before Latest Fiscal Year	193
Gross charge-offs Originated Three Years Before Latest Fiscal Year	86
Gross charge-offs Originated Four Years Before Latest Fiscal Year	51
Gross charge-offs Prior	249
Gross charge-offs Revolving Loans	1,049
Gross charge-offs Total loans	2,003
Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	95,747	4,114,605
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	4,102,540	2,416,053
Financing Receivable Originated Two Years Before Latest Fiscal Year	2,359,966	1,265,652
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,220,146	499,087
Financing Receivable Originated Four Years Before Latest Fiscal Year	462,680	388,294
Prior	1,048,377	706,912
Revolving Loans	1,252,295	1,204,870
Total	10,541,751	10,595,473
Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		13,967
Financing Receivable Originated Two Years Before Latest Fiscal Year	20,671	3,552
Financing Receivable Originated Three Years Before Latest Fiscal Year	7,063	13,137
Financing Receivable Originated Four Years Before Latest Fiscal Year	12,869	21,501
Prior	30,386	9,450
Revolving Loans	4,824	5,598
Total	75,813	67,205
Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		5,919
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	5,864	14,756
Financing Receivable Originated Two Years Before Latest Fiscal Year	9,783	2,867
Financing Receivable Originated Three Years Before Latest Fiscal Year	2,598	12,471
Financing Receivable Originated Four Years Before Latest Fiscal Year	11,981
Prior	14,926	17,604
Revolving Loans	7,087	9,898
Total	52,239	63,515
Residential Properties
Financing Receivable Recorded Investment [Line Items]
Total	6,360,811	6,377,224
Multifamily
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	16,080	2,399,360
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	2,398,706	1,552,311
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,547,733	795,263
Financing Receivable Originated Three Years Before Latest Fiscal Year	793,127	306,691
Financing Receivable Originated Four Years Before Latest Fiscal Year	302,961	155,442
Prior	289,923	148,167
Total	5,348,530	5,357,234
Multifamily | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	16,080	2,399,360
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	2,398,706	1,552,311
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,547,733	795,263
Financing Receivable Originated Three Years Before Latest Fiscal Year	793,127	301,025
Financing Receivable Originated Four Years Before Latest Fiscal Year	297,324	145,675
Prior	278,675	146,622
Total	5,331,645	5,340,256
Multifamily | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated Three Years Before Latest Fiscal Year		5,666
Financing Receivable Originated Four Years Before Latest Fiscal Year	5,637	9,767
Prior	11,248	1,545
Total	16,885	16,978
Single family
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	9,505	270,589
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	269,712	276,244
Financing Receivable Originated Two Years Before Latest Fiscal Year	274,013	96,183
Financing Receivable Originated Three Years Before Latest Fiscal Year	95,026	40,010
Financing Receivable Originated Four Years Before Latest Fiscal Year	39,831	49,676
Prior	256,702	218,643
Revolving Loans	67,492	68,645
Total	1,012,281	1,019,990
Single family | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	9,505	270,589
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	269,712	276,244
Financing Receivable Originated Two Years Before Latest Fiscal Year	274,013	96,183
Financing Receivable Originated Three Years Before Latest Fiscal Year	95,026	40,010
Financing Receivable Originated Four Years Before Latest Fiscal Year	39,831	49,676
Prior	253,304	215,209
Revolving Loans	67,462	68,575
Total	1,008,853	1,016,486
Single family | Special mention
Financing Receivable Recorded Investment [Line Items]
Revolving Loans		25
Total		25
Single family | Substandard
Financing Receivable Recorded Investment [Line Items]
Prior	3,398	3,434
Revolving Loans	30	45
Total	3,428	3,479
Commercial real estate
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	13,589	229,422
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	227,343	186,164
Financing Receivable Originated Two Years Before Latest Fiscal Year	166,427	147,187
Financing Receivable Originated Three Years Before Latest Fiscal Year	137,657	111,709
Financing Receivable Originated Four Years Before Latest Fiscal Year	102,821	183,194
Prior	506,682	344,387
Total	1,154,519	1,202,063
Financing Receivable Recorded Investment
Gross charge-offs Prior	249
Gross charge-offs Total loans	249
Commercial real estate | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	13,589	223,503
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	221,479	158,363
Financing Receivable Originated Two Years Before Latest Fiscal Year	157,009	144,105
Financing Receivable Originated Three Years Before Latest Fiscal Year	134,635	93,960
Financing Receivable Originated Four Years Before Latest Fiscal Year	85,223	171,460
Prior	477,039	325,048
Total	1,088,974	1,116,439
Commercial real estate | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		13,425
Financing Receivable Originated Two Years Before Latest Fiscal Year		2,340
Financing Receivable Originated Three Years Before Latest Fiscal Year	2,324	7,088
Financing Receivable Originated Four Years Before Latest Fiscal Year	7,040	11,734
Prior	19,138	7,905
Total	28,502	42,492
Commercial real estate | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year		5,919
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	5,864	14,376
Financing Receivable Originated Two Years Before Latest Fiscal Year	9,418	742
Financing Receivable Originated Three Years Before Latest Fiscal Year	698	10,661
Financing Receivable Originated Four Years Before Latest Fiscal Year	10,558
Prior	10,505	11,434
Total	37,043	43,132
Land and Construction
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	4,205	43,846
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	41,435	58,268
Financing Receivable Originated Two Years Before Latest Fiscal Year	62,677	47,212
Financing Receivable Originated Three Years Before Latest Fiscal Year	48,764	854
Financing Receivable Originated Four Years Before Latest Fiscal Year	842	5,044
Prior	7,293	2,406
Total	165,216	157,630
Land and Construction | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	4,205	43,846
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	41,435	58,268
Financing Receivable Originated Two Years Before Latest Fiscal Year	62,677	47,212
Financing Receivable Originated Three Years Before Latest Fiscal Year	48,764	854
Financing Receivable Originated Four Years Before Latest Fiscal Year	842	5,044
Prior	7,293	2,406
Total	165,216	157,630
Commercial and Industrial Loans
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	52,358	1,176,851
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,171,201	370,697
Financing Receivable Originated Two Years Before Latest Fiscal Year	338,501	186,226
Financing Receivable Originated Three Years Before Latest Fiscal Year	155,233	64,960
Financing Receivable Originated Four Years Before Latest Fiscal Year	40,743	16,306
Prior	32,916	20,294
Revolving Loans	1,194,415	1,149,424
Total	2,985,367	2,984,758
Financing Receivable Recorded Investment
Gross charge-offs Originated In Fiscal Year Before Latest Fiscal Year	375
Gross charge-offs Originated Two Years Before Latest Fiscal Year	193
Gross charge-offs Originated Three Years Before Latest Fiscal Year	86
Gross charge-offs Originated Four Years Before Latest Fiscal Year	51
Gross charge-offs Revolving Loans	1,047
Gross charge-offs Total loans	1,752
Commercial and Industrial Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	52,358	1,176,851
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	1,171,201	369,775
Financing Receivable Originated Two Years Before Latest Fiscal Year	317,465	182,889
Financing Receivable Originated Three Years Before Latest Fiscal Year	148,594	62,767
Financing Receivable Originated Four Years Before Latest Fiscal Year	39,128	16,306
Prior	31,893	17,558
Revolving Loans	1,182,534	1,133,998
Total	2,943,173	2,960,144
Commercial and Industrial Loans | Special mention
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		542
Financing Receivable Originated Two Years Before Latest Fiscal Year	20,671	1,212
Financing Receivable Originated Three Years Before Latest Fiscal Year	4,739	383
Financing Receivable Originated Four Years Before Latest Fiscal Year	192
Revolving Loans	4,824	5,573
Total	30,426	7,710
Commercial and Industrial Loans | Substandard
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year		380
Financing Receivable Originated Two Years Before Latest Fiscal Year	365	2,125
Financing Receivable Originated Three Years Before Latest Fiscal Year	1,900	1,810
Financing Receivable Originated Four Years Before Latest Fiscal Year	1,423
Prior	1,023	2,736
Revolving Loans	7,057	9,853
Total	11,768	16,904
Consumer Loans
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	10	456
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	7	1,092
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,069
Financing Receivable Originated Three Years Before Latest Fiscal Year		471
Financing Receivable Originated Four Years Before Latest Fiscal Year	332	133
Prior	173	69
Revolving Loans	2,299	2,297
Total	3,890	4,518
Financing Receivable Recorded Investment
Gross charge-offs Revolving Loans	2
Gross charge-offs Total loans	2
Consumer Loans | Pass
Financing Receivable Recorded Investment [Line Items]
Financing Receivable Originated In Current Fiscal Year	10	456
Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year	7	1,092
Financing Receivable Originated Two Years Before Latest Fiscal Year	1,069
Financing Receivable Originated Three Years Before Latest Fiscal Year		471
Financing Receivable Originated Four Years Before Latest Fiscal Year	332	133
Prior	173	69
Revolving Loans	2,299	2,297
Total	$ 3,890	$ 4,518