Loans, Past Due (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Recorded investment of past due [Abstract]
Total past due	$ 16,514	$ 12,204
Current	1,041,241	985,683
PCI	2,576	2,638
Total financing receivables	1,060,331	1,000,525
90 Days or greater and accruing	302	555
Financing receivables on nonaccrual status [Abstract]
Total past due and non-accrual	13,085	8,160
Current and non-accrual	1,445	2,011
PCI Loans considered non accrual	0	0
Financing receivable nonaccrual status	14,530	10,171
Financing receivables on accrual status [Abstract]
Total past due and still accruing	3,429	4,044
Current and still accruing	1,039,796	983,672
PCI Loans still accruing	2,576	2,638
Total financing receivables and still accruing	$ 1,045,801	990,354
Minimum [Member]
Financing receivables on nonaccrual status [Abstract]
Period of past due after which loans considered as non accrual	90 days
30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	$ 3,174	3,053
Financing receivables on nonaccrual status [Abstract]
Total past due and non-accrual	326	816
Financing receivables on accrual status [Abstract]
Total past due and still accruing	2,848	2,237
60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	1,649	1,533
Financing receivables on nonaccrual status [Abstract]
Total past due and non-accrual	1,370	281
Financing receivables on accrual status [Abstract]
Total past due and still accruing	279	1,252
90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	11,691	7,618
Financing receivables on nonaccrual status [Abstract]
Total past due and non-accrual	11,389	7,063
Financing receivables on accrual status [Abstract]
Total past due and still accruing	302	555
Real Estate Loans [Member] | Mortgages [Member]
Recorded investment of past due [Abstract]
Total past due	1,537	2,168
Current	153,054	152,144
PCI	30	33
Total financing receivables	154,621	154,345
90 Days or greater and accruing	1	218
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	1,263	1,274
Real Estate Loans [Member] | Mortgages [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	661	996
Real Estate Loans [Member] | Mortgages [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	191	362
Real Estate Loans [Member] | Mortgages [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	685	810
Real Estate Loans [Member] | Home Equity [Member]
Recorded investment of past due [Abstract]
Total past due	192	441
Current	58,442	59,693
PCI	0	0
Total financing receivables	58,634	60,134
90 Days or greater and accruing	0	0
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	86	112
Real Estate Loans [Member] | Home Equity [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	125	277
Real Estate Loans [Member] | Home Equity [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	0	86
Real Estate Loans [Member] | Home Equity [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	67	78
Real Estate Loans [Member] | Commercial [Member]
Recorded investment of past due [Abstract]
Total past due	7,282	6,228
Current	304,355	300,396
PCI	1,345	1,460
Total financing receivables	312,982	308,084
90 Days or greater and accruing	300	162
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	6,445	5,192
Real Estate Loans [Member] | Commercial [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	1,576	1,353
Real Estate Loans [Member] | Commercial [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	1,109	1,010
Real Estate Loans [Member] | Commercial [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	4,597	3,865
Real Estate Loans [Member] | Agricultural [Member]
Recorded investment of past due [Abstract]
Total past due	3,259	447
Current	276,627	238,808
PCI	683	702
Total financing receivables	280,569	239,957
90 Days or greater and accruing	0	30
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	3,259	175
Real Estate Loans [Member] | Agricultural [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	0	242
Real Estate Loans [Member] | Agricultural [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	6	0
Real Estate Loans [Member] | Agricultural [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	3,253	205
Real Estate Loans [Member] | Construction [Member]
Recorded investment of past due [Abstract]
Total past due	0	133
Current	30,262	13,369
PCI	0	0
Total financing receivables	30,262	13,502
90 Days or greater and accruing	0	0
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	0	133
Real Estate Loans [Member] | Construction [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	0	0
Real Estate Loans [Member] | Construction [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	0	0
Real Estate Loans [Member] | Construction [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	0	133
Consumer [Member]
Recorded investment of past due [Abstract]
Total past due	77	135
Current	9,625	9,809
PCI	0	0
Total financing receivables	9,702	9,944
90 Days or greater and accruing	1	7
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	22	42
Consumer [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	69	53
Consumer [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	7	33
Consumer [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	1	49
Other Commercial Loans [Member]
Recorded investment of past due [Abstract]
Total past due	2,982	2,504
Current	68,719	69,066
PCI	518	443
Total financing receivables	72,219	72,013
90 Days or greater and accruing	0	32
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	2,269	2,637
Other Commercial Loans [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	662	132
Other Commercial Loans [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	141	0
Other Commercial Loans [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	2,179	2,372
Other Agricultural Loans [Member]
Recorded investment of past due [Abstract]
Total past due	1,185	148
Current	38,732	37,661
PCI	0	0
Total financing receivables	39,917	37,809
90 Days or greater and accruing	0	106
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	1,186	606
Other Agricultural Loans [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	81	0
Other Agricultural Loans [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	195	42
Other Agricultural Loans [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	909	106
State and Political Subdivision Loans [Member]
Recorded investment of past due [Abstract]
Total past due	0	0
Current	101,425	104,737
PCI	0	0
Total financing receivables	101,425	104,737
90 Days or greater and accruing	0	0
Financing receivables on nonaccrual status [Abstract]
Financing receivable nonaccrual status	0	0
State and Political Subdivision Loans [Member] | 30 to 59 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	0	0
State and Political Subdivision Loans [Member] | 60 to 89 Days Past Due [Member]
Recorded investment of past due [Abstract]
Total past due	0	0
State and Political Subdivision Loans [Member] | 90 Days Or Greater [Member]
Recorded investment of past due [Abstract]
Total past due	$ 0	$ 0