Loans, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	$ 2,226,932	$ 2,124,916	$ 2,076,079
Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	32,457	29,829
Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	319,687	300,564
Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,549,273	1,455,498
Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	207,247	215,156
Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	55,116	86,489
Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	63,152	37,380
Agricultural [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	88,104	101,588	93,533
Agricultural [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,776	1,786
Agricultural [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	13,178	15,959
Agricultural [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	39,017	36,819
Agricultural [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	8,030	18,064
Agricultural [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	11,471	25,356
Agricultural [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	14,632	3,604
Commercial and Financial [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	188,365	184,199	173,029
Commercial and Financial [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	4,437	3,298
Commercial and Financial [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	37,892	38,764
Commercial and Financial [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	110,595	102,188
Commercial and Financial [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	20,612	27,181
Commercial and Financial [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	9,328	8,231
Commercial and Financial [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	5,501	4,537
Real Estate: Construction, 1 to 4 family residential [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	59,273	51,346
Real Estate: Construction, 1 to 4 family residential [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	0	0
Real Estate: Construction, 1 to 4 family residential [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,677	1,898
Real Estate: Construction, 1 to 4 family residential [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	46,282	34,357
Real Estate: Construction, 1 to 4 family residential [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	8,147	8,684
Real Estate: Construction, 1 to 4 family residential [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	657	5,842
Real Estate: Construction, 1 to 4 family residential [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	2,510	565
Real Estate: Construction, land development and commercial [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	119,547	83,121
Real Estate: Construction, land development and commercial [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	247	260
Real Estate: Construction, land development and commercial [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	16,386	11,570
Real Estate: Construction, land development and commercial [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	71,625	52,731
Real Estate: Construction, land development and commercial [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	24,109	11,550
Real Estate: Construction, land development and commercial [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	6,125	6,542
Real Estate: Construction, land development and commercial [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,055	468
Real Estate: Mortgage, farmland [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	193,819	187,856	$ 179,981
Real Estate: Mortgage, farmland [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	2,364	2,559
Real Estate: Mortgage, farmland [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	46,577	31,186
Real Estate: Mortgage, farmland [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	101,256	112,038
Real Estate: Mortgage, farmland [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	28,214	27,304
Real Estate: Mortgage, farmland [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	5,933	11,181
Real Estate: Mortgage, farmland [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	9,475	3,588
Real Estate: Mortgage, 1 to 4 family first liens [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	761,105	727,160
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	687	426
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	14,713	15,773
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	654,690	620,731
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	53,881	55,499
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	13,676	16,237
Real Estate: Mortgage, 1 to 4 family first liens [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	23,458	18,494
Real Estate: Mortgage, 1 to 4 family junior liens [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	122,588	117,873
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	0	0
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	2,384	2,992
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	112,673	107,091
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	4,035	4,198
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,693	1,846
Real Estate: Mortgage, 1 to 4 family junior liens [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,803	1,746
Real Estate: Mortgage, multi-family [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	292,190	271,974
Real Estate: Mortgage, multi-family [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	5,642	6,651
Real Estate: Mortgage, multi-family [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	62,796	64,002
Real Estate: Mortgage, multi-family [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	184,733	166,193
Real Estate: Mortgage, multi-family [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	36,501	29,732
Real Estate: Mortgage, multi-family [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	1,972	4,873
Real Estate: Mortgage, multi-family [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	546	523
Real Estate: Mortgage, commercial [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	327,024	323,409
Real Estate: Mortgage, commercial [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	14,999	12,484
Real Estate: Mortgage, commercial [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	88,397	81,305
Real Estate: Mortgage, commercial [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	192,609	187,728
Real Estate: Mortgage, commercial [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	22,929	32,141
Real Estate: Mortgage, commercial [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	4,094	6,183
Real Estate: Mortgage, commercial [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	3,996	3,568
Loans to individuals [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	24,355	24,019
Loans to individuals [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	0	0
Loans to individuals [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	89	70
Loans to individuals [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	23,640	23,197
Loans to individuals [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	283	285
Loans to individuals [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	167	198
Loans to individuals [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	176	269
Obligations of state and political subdivisions [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	50,562	52,371
Obligations of state and political subdivisions [Member] | Excellent [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	2,305	2,365
Obligations of state and political subdivisions [Member] | Good [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	35,598	37,045
Obligations of state and political subdivisions [Member] | Satisfactory [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	12,153	12,425
Obligations of state and political subdivisions [Member] | Monitor [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	506	518
Obligations of state and political subdivisions [Member] | Special Mention [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	0	0
Obligations of state and political subdivisions [Member] | Substandard [Member]
Summary of credit quality indicators by type of loans [Abstract]
Loans and receivable	$ 0	$ 18