LOANS - Summary of Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 2,372,436	$ 1,129,064
Net deferred loan costs and fees	(199)	(170)
Business Activities Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,048	8,928
Current	1,196,581	1,120,136
Total loans	1,202,629	1,129,064
Past Due 90 days and Accruing	0	0
Net deferred loan costs and fees	(199)	(170)
Business Activities Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,418	5,074
Business Activities Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	320	1,029
Business Activities Loans | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,310	2,825
Business Activities Loans | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,658	2,414
Current	443,279	415,875
Total loans	444,937	418,289
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial Real Estate | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	8,315	14,695
Total loans	8,315	14,695
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial Real Estate | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,658	2,414
Current	434,964	401,180
Total loans	436,622	403,594
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial Real Estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	184	195
Business Activities Loans | Commercial Real Estate | 30-59 Days Past Due | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Commercial Real Estate | 30-59 Days Past Due | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	184	195
Business Activities Loans | Commercial Real Estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13	554
Business Activities Loans | Commercial Real Estate | 60-89 Days Past Due | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Commercial Real Estate | 60-89 Days Past Due | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13	554
Business Activities Loans | Commercial Real Estate | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,461	1,665
Business Activities Loans | Commercial Real Estate | 90 Days or Greater Past Due | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Commercial Real Estate | 90 Days or Greater Past Due | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,461	1,665
Business Activities Loans | Commercial and Industrial Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	509	538
Current	183,677	150,702
Total loans	184,186	151,240
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial and Industrial Loans | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	248	307
Current	120,054	103,279
Total loans	120,302	103,586
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial and Industrial Loans | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	261	231
Current	32,360	31,577
Total loans	32,621	31,808
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial and Industrial Loans | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	31,263	15,846
Total loans	31,263	15,846
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial and Industrial Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	34	292
Business Activities Loans | Commercial and Industrial Loans | 30-59 Days Past Due | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	34	61
Business Activities Loans | Commercial and Industrial Loans | 30-59 Days Past Due | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	231
Business Activities Loans | Commercial and Industrial Loans | 30-59 Days Past Due | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Commercial and Industrial Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	134	45
Business Activities Loans | Commercial and Industrial Loans | 60-89 Days Past Due | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9	45
Business Activities Loans | Commercial and Industrial Loans | 60-89 Days Past Due | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	125	0
Business Activities Loans | Commercial and Industrial Loans | 60-89 Days Past Due | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	341	201
Business Activities Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	205	201
Business Activities Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	136	0
Business Activities Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Commercial Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,167	2,952
Current	626,956	566,577
Total loans	629,123	569,529
Past Due 90 days and Accruing	0	0
Business Activities Loans | Commercial Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	218	487
Business Activities Loans | Commercial Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	147	599
Business Activities Loans | Commercial Loans | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,802	1,866
Business Activities Loans | Residential Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,644	5,851
Current	514,912	500,761
Total loans	518,556	506,612
Past Due 90 days and Accruing	0	0
Business Activities Loans | Residential Mortgages | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,644	5,851
Current	514,912	500,761
Total loans	518,556	506,612
Past Due 90 days and Accruing	0	0
Business Activities Loans | Residential Mortgages | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,963	4,484
Business Activities Loans | Residential Mortgages | 30-59 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,963	4,484
Business Activities Loans | Residential Mortgages | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	173	429
Business Activities Loans | Residential Mortgages | 60-89 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	173	429
Business Activities Loans | Residential Mortgages | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	508	938
Business Activities Loans | Residential Mortgages | 90 Days or Greater Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	508	938
Business Activities Loans | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	237	125
Current	54,912	52,968
Total loans	55,149	53,093
Past Due 90 days and Accruing	0	0
Business Activities Loans | Consumer | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	128	15
Current	47,890	46,906
Total loans	48,018	46,921
Past Due 90 days and Accruing	0	0
Business Activities Loans | Consumer | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	109	110
Current	7,022	6,062
Total loans	7,131	6,172
Past Due 90 days and Accruing	0	0
Business Activities Loans | Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	237	103
Business Activities Loans | Consumer | 30-59 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	128	0
Business Activities Loans | Consumer | 30-59 Days Past Due | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	109	103
Business Activities Loans | Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	1
Business Activities Loans | Consumer | 60-89 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Business Activities Loans | Consumer | 60-89 Days Past Due | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	1
Business Activities Loans | Consumer | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	21
Business Activities Loans | Consumer | 90 Days or Greater Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	15
Business Activities Loans | Consumer | 90 Days or Greater Past Due | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	6
Acquired Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,106
Acquired Credit Impaired	17,025
Total loans	1,169,807	0
Past Due 90 days and Accruing	0
Net deferred loan costs and fees	0	0
Acquired Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,626
Acquired Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	480
Acquired Loans | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,167
Acquired Credit Impaired	11,853
Total loans	334,897	0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial Real Estate | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Credit Impaired	516
Total loans	17,315	0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial Real Estate | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,167
Acquired Credit Impaired	11,337
Total loans	317,582	0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial Real Estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	742
Acquired Loans | Commercial Real Estate | 30-59 Days Past Due | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial Real Estate | 30-59 Days Past Due | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	742
Acquired Loans | Commercial Real Estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	425
Acquired Loans | Commercial Real Estate | 60-89 Days Past Due | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial Real Estate | 60-89 Days Past Due | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	425
Acquired Loans | Commercial Real Estate | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial Real Estate | 90 Days or Greater Past Due | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial Real Estate | 90 Days or Greater Past Due | Commercial real estate other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	218
Acquired Credit Impaired	1,142
Total loans	125,809	0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial and Industrial Loans | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	218
Acquired Credit Impaired	1,142
Total loans	82,761	0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial and Industrial Loans | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Credit Impaired	0
Total loans	643	0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial and Industrial Loans | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Credit Impaired	0
Total loans	42,405	$ 0
Past Due 90 days and Accruing	0
Acquired Loans | Commercial and Industrial Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	218
Acquired Loans | Commercial and Industrial Loans | 30-59 Days Past Due | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	218
Acquired Loans | Commercial and Industrial Loans | 30-59 Days Past Due | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 30-59 Days Past Due | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 60-89 Days Past Due | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 60-89 Days Past Due | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 60-89 Days Past Due | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due | Commercial other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due | Agricultural and other loans to farmers
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and Industrial Loans | 90 Days or Greater Past Due | Tax exempt loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,385
Acquired Credit Impaired	12,995
Total loans	460,706
Past Due 90 days and Accruing	0
Acquired Loans | Commercial Loans | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	960
Acquired Loans | Commercial Loans | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	425
Acquired Loans | Commercial Loans | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Residential Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,409
Acquired Credit Impaired	3,819
Total loans	636,880
Past Due 90 days and Accruing	0
Acquired Loans | Residential Mortgages | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,409
Acquired Credit Impaired	3,819
Total loans	636,880
Past Due 90 days and Accruing	0
Acquired Loans | Residential Mortgages | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,354
Acquired Loans | Residential Mortgages | 30-59 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,354
Acquired Loans | Residential Mortgages | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	55
Acquired Loans | Residential Mortgages | 60-89 Days Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	55
Acquired Loans | Residential Mortgages | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Residential Mortgages | 90 Days or Greater Past Due | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	312
Acquired Credit Impaired	211
Total loans	72,221
Past Due 90 days and Accruing	0
Acquired Loans | Consumer | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	309
Acquired Credit Impaired	192
Total loans	68,374
Past Due 90 days and Accruing	0
Acquired Loans | Consumer | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3
Acquired Credit Impaired	19
Total loans	3,847
Past Due 90 days and Accruing	0
Acquired Loans | Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	312
Acquired Loans | Consumer | 30-59 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	309
Acquired Loans | Consumer | 30-59 Days Past Due | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3
Acquired Loans | Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | 60-89 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | 60-89 Days Past Due | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | 90 Days or Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | 90 Days or Greater Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | 90 Days or Greater Past Due | Consumer other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 0