INCOME TAXES - Deferred tax assets and liabilities (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Assets:    
Allowance for loan losses $ 5,766,000 $ 6,435,000
Deferred compensation 2,136,000 2,029,000
Loans acquired in FDIC assisted transactions   3,878,000
Investments acquired in FDIC assisted transactions   3,504,000
Loans 1,972,000 2,889,000
Write-down of other real estate owned 70,000 1,758,000
Tax credits 3,106,000 3,076,000
Nonaccrual interest 1,007,000 727,000
Unrealized loss on securities 387,000  
Intangible assets 292,000  
Stock compensation 689,000 268,000
Other, net 777,000 2,160,000
Deferred tax assets 16,202,000 26,724,000
Valuation allowance (631,000)  
Deferred tax assets, net of valuation allowance 15,571,000 26,724,000
Liabilities:    
Premises and equipment 1,268,000 2,414,000
Unrealized gain on securities   4,061,000
Mortgage servicing rights 15,092,000 12,084,000
Fair value adjustment on trust preferred debentures 6,023,000 6,387,000
Federal Home Loan Bank stock dividends 227,000 235,000
Indemnification asset due from FDIC   (82,000)
Deferred loan fees, net of costs 136,000 103,000
Intangible assets   26,000
Accounting method changes 1,156,000  
Other, net 267,000  
Deferred tax liabilities 24,169,000 25,228,000
Deferred tax (liabilities) assets, net (8,598,000)  
Deferred tax (liabilities) assets, net   1,496,000
Accumulation of prior year’s earnings representing tax bad debt deductions 3,100,000 3,100,000
Operating loss carryforwards 0  
Unrecognized tax benefits 0 0
Interest or penalties relative to unrecognized tax benefits 0 $ 0
State tax credit carryforwards Valuation allowance 631,000  
Federal    
Liabilities:    
Tax credit carryforward 1,500,000  
State    
Liabilities:    
Tax credit carryforward $ 920,000  
Period for tax credit carryforward. 5 years