ALLOWANCE FOR LOAN LOSSES - Segregated by loan class (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Loan losses segregated by loan class
Beginning balance	$ 25,006	$ 25,315	$ 25,315
Provision (recapture) for loan loss	(1,388)	3,925	4,575
Charge-offs	(874)	(2,888)	(6,079)
Recoveries	1,013	744	1,195
Net (charge-offs) recoveries	139	(2,144)	(4,884)
Ending balance	23,757	27,096	25,006
Specific reserve
Loan losses segregated by loan class
Beginning balance	668
Ending balance	556	2,765	668
General reserve
Loan losses segregated by loan class
Beginning balance	24,338
Ending balance	23,201	24,331	24,338
Commercial and industrial
Loan losses segregated by loan class
Beginning balance	6,409	4,746	4,746
Provision (recapture) for loan loss	631	3,438	5,537
Charge-offs	(791)	(1,792)	(4,884)
Recoveries	945	666	1,010
Net (charge-offs) recoveries	154	(1,126)	(3,874)
Ending balance	7,194	7,058	6,409
Commercial and industrial \| Specific reserve
Loan losses segregated by loan class
Beginning balance	462
Ending balance	424	1,770	462
Commercial and industrial \| General reserve
Loan losses segregated by loan class
Beginning balance	5,947
Ending balance	6,770	5,288	5,947
Commercial real estate
Loan losses segregated by loan class
Beginning balance	10,770	7,058	7,058
Provision (recapture) for loan loss	(1,137)	548	4,193
Charge-offs		(549)	(589)
Recoveries	7	4	108
Net (charge-offs) recoveries	7	(545)	(481)
Ending balance	9,640	7,061	10,770
Commercial real estate \| Specific reserve
Loan losses segregated by loan class
Beginning balance	206
Ending balance		644	206
Commercial real estate \| General reserve
Loan losses segregated by loan class
Beginning balance	10,564
Ending balance	9,640	6,417	10,564
Construction and development
Loan losses segregated by loan class
Beginning balance	4,598	4,504	4,504
Provision (recapture) for loan loss	(1,234)	385	94
Ending balance	3,364	4,889	4,598
Construction and development \| General reserve
Loan losses segregated by loan class
Beginning balance	4,598
Ending balance	3,364	4,889	4,598
One to four family residential
Loan losses segregated by loan class
Beginning balance	1,286	2,295	2,295
Provision (recapture) for loan loss	(16)	(198)	(1,012)
Charge-offs		(3)	(3)
Recoveries	12	5	6
Net (charge-offs) recoveries	12	2	3
Ending balance	1,282	2,099	1,286
One to four family residential \| Specific reserve
Loan losses segregated by loan class
Ending balance	132
One to four family residential \| General reserve
Loan losses segregated by loan class
Beginning balance	1,286
Ending balance	1,150	2,099	1,286
Multi‑family residential
Loan losses segregated by loan class
Beginning balance	916	762	762
Provision (recapture) for loan loss	444	193	154
Ending balance	1,360	955	916
Multi‑family residential \| General reserve
Loan losses segregated by loan class
Beginning balance	916
Ending balance	1,360	955	916
Consumer
Loan losses segregated by loan class
Beginning balance	353	363	363
Provision (recapture) for loan loss	332	219	222
Charge-offs	(83)	(278)	(277)
Recoveries	24	44	45
Net (charge-offs) recoveries	(59)	(234)	(232)
Ending balance	626	348	353
Consumer \| Specific reserve
Loan losses segregated by loan class
Ending balance		1
Consumer \| General reserve
Loan losses segregated by loan class
Beginning balance	353
Ending balance	626	347	353
Agriculture
Loan losses segregated by loan class
Beginning balance	79	93	93
Provision (recapture) for loan loss	(27)	245	227
Charge-offs		(266)	(267)
Recoveries	17	25	26
Net (charge-offs) recoveries	17	(241)	(241)
Ending balance	69	97	79
Agriculture \| General reserve
Loan losses segregated by loan class
Beginning balance	79
Ending balance	69	97	79
Other
Loan losses segregated by loan class
Beginning balance	595	5,494	5,494
Provision (recapture) for loan loss	(381)	(905)	(4,840)
Charge-offs			(59)
Recoveries	8
Net (charge-offs) recoveries	8		(59)
Ending balance	222	4,589	595
Other \| Specific reserve
Loan losses segregated by loan class
Ending balance		350
Other \| General reserve
Loan losses segregated by loan class
Beginning balance	595
Ending balance	222	$ 4,239	595
Unfunded Loan Commitment
Loan losses segregated by loan class
Beginning balance	366
Ending balance	$ 378		$ 366

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount, after recoveries, of loans and leases that have been written-off.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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