LOANS AND CREDIT QUALITY - Activity in Allowance for Credit Losses by Loan Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allowance for credit losses by loan portfolio
Beginning balance	$ 44,628	$ 40,982	$ 42,913	$ 39,116
Charge-offs	(68)	(160)	(209)	(1,055)
Recoveries	74	282	430	1,293
(Reversal of) Provision	0	750	1,500	2,500
Ending balance	44,634	41,854	44,634	41,854
Consumer loans [Member]
Allowance for credit losses by loan portfolio
Beginning balance	15,103	15,940	15,929	16,493
Charge-offs	(68)	(150)	(209)	(392)
Recoveries	60	104	355	609
(Reversal of) Provision	(390)	159	(1,370)	(657)
Ending balance	14,705	16,053	14,705	16,053
Consumer loans [Member] \| Single family [Member]
Allowance for credit losses by loan portfolio
Beginning balance	7,540	8,594	8,217	9,412
Charge-offs	0	(43)	0	(43)
Recoveries	1	2	143	284
(Reversal of) Provision	(321)	(46)	(1,140)	(1,146)
Ending balance	7,220	8,507	7,220	8,507
Consumer loans [Member] \| Home equity and other [Member]
Allowance for credit losses by loan portfolio
Beginning balance	7,563	7,346	7,712	7,081
Charge-offs	(68)	(107)	(209)	(349)
Recoveries	59	102	212	325
(Reversal of) Provision	(69)	205	(230)	489
Ending balance	7,485	7,546	7,485	7,546
Commercial loans [Member] \| Non-owner occupied commercial real estate [Member]
Allowance for credit losses by loan portfolio
Beginning balance	6,151	4,764	5,496	4,755
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
(Reversal of) Provision	330	249	985	258
Ending balance	6,481	5,013	6,481	5,013
Commercial loans [Member] \| Multifamily [Member]
Allowance for credit losses by loan portfolio
Beginning balance	7,047	5,017	5,754	3,895
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
(Reversal of) Provision	(357)	608	936	1,730
Ending balance	6,690	5,625	6,690	5,625
Commercial loans [Member] \| Construction/land development [Member]
Allowance for credit losses by loan portfolio
Beginning balance	9,707	9,205	9,539	8,677
Charge-offs	0	0	0	0
Recoveries	1	170	48	513
(Reversal of) Provision	99	(94)	220	91
Ending balance	9,807	9,281	9,807	9,281
Commercial loans [Member] \| Owner occupied commercial real estate [Member]
Allowance for credit losses by loan portfolio
Beginning balance	3,462	3,032	3,282	2,960
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
(Reversal of) Provision	139	111	319	183
Ending balance	3,601	3,143	3,601	3,143
Commercial loans [Member] \| Commercial business [Member]
Allowance for credit losses by loan portfolio
Beginning balance	3,158	3,024	2,913	2,336
Charge-offs	0	(10)	0	(663)
Recoveries	13	8	27	171
(Reversal of) Provision	179	(283)	410	895
Ending balance	3,350	2,739	3,350	2,739
Real Estate Sector [Member] \| Commercial loans [Member]
Allowance for credit losses by loan portfolio
Beginning balance	22,905	18,986	20,789	17,327
Charge-offs	0	0	0	0
Recoveries	1	170	48	513
(Reversal of) Provision	72	763	2,141	2,079
Ending balance	22,978	19,919	22,978	19,919
Commercial and Industrial Sector [Member] \| Commercial loans [Member]
Allowance for credit losses by loan portfolio
Beginning balance	6,620	6,056	6,195	5,296
Charge-offs	0	(10)	0	(663)
Recoveries	13	8	27	171
(Reversal of) Provision	318	(172)	729	1,078
Ending balance	$ 6,951	$ 5,882	$ 6,951	$ 5,882

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

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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