LOANS AND CREDIT QUALITY - Activity in Allowance for Credit Losses by Loan Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Allowance for credit losses by loan portfolio
Beginning balance	$ 47,123	$ 64,294
Charge-offs	(44)	(126)
Recoveries	88	250
Provision	(9,223)	(371)
Ending balance	37,944	64,047
Commercial loans \| Real Estate Sector
Allowance for credit losses by loan portfolio
Beginning balance	21,486	27,935
Charge-offs	0	0
Recoveries	0	0
Provision	(1,400)	227
Ending balance	20,086	28,162
Commercial loans \| Commercial and Industrial Sector
Allowance for credit losses by loan portfolio
Beginning balance	17,279	22,037
Charge-offs	(11)	0
Recoveries	24	74
Provision	(6,846)	260
Ending balance	10,446	22,371
Commercial loans \| Non-owner occupied CRE
Allowance for credit losses by loan portfolio
Beginning balance	7,509	8,845
Charge-offs	0	0
Recoveries	0	0
Provision	(5,215)	373
Ending balance	2,294	9,218
Commercial loans \| Multifamily
Allowance for credit losses by loan portfolio
Beginning balance	5,854	6,072
Charge-offs	0	0
Recoveries	0	0
Provision	2,573	897
Ending balance	8,427	6,969
Commercial loans \| Multifamily construction
Allowance for credit losses by loan portfolio
Beginning balance	507	4,903
Charge-offs	0	0
Recoveries	0	0
Provision	(51)	(967)
Ending balance	456	3,936
Commercial loans \| CRE construction
Allowance for credit losses by loan portfolio
Beginning balance	150	1,670
Charge-offs	0	0
Recoveries	0	0
Provision	34	238
Ending balance	184	1,908
Commercial loans \| Single family construction
Allowance for credit losses by loan portfolio
Beginning balance	6,411	5,130
Charge-offs	0	0
Recoveries	0
Provision	1,324	(123)
Ending balance	7,735	5,007
Commercial loans \| Single family construction to permanent
Allowance for credit losses by loan portfolio
Beginning balance	1,055	1,315
Charge-offs	0	0
Recoveries	0	0
Provision	(65)	(191)
Ending balance	990	1,124
Commercial loans \| Owner occupied CRE
Allowance for credit losses by loan portfolio
Beginning balance	5,006	4,994
Charge-offs	0	0
Recoveries	0	0
Provision	(1,470)	272
Ending balance	3,536	5,266
Commercial loans \| Commercial business
Allowance for credit losses by loan portfolio
Beginning balance	12,273	17,043
Charge-offs	(11)	0
Recoveries	24	74
Provision	(5,376)	(12)
Ending balance	6,910	17,105
Consumer loans
Allowance for credit losses by loan portfolio
Beginning balance	8,358	14,322
Charge-offs	(33)	(126)
Recoveries	64	176
Provision	(977)	(858)
Ending balance	7,412	13,514
Consumer loans \| Single family
Allowance for credit losses by loan portfolio
Beginning balance	4,394	6,906
Charge-offs	0	(70)
Recoveries	4	120
Provision	(636)	(221)
Ending balance	3,762	6,735
Consumer loans \| Home equity and other
Allowance for credit losses by loan portfolio
Beginning balance	3,964	7,416
Charge-offs	(33)	(56)
Recoveries	60	56
Provision	(341)	(637)
Ending balance	$ 3,650	$ 6,779

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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