Credit Quality and Nonperforming Assets - Past Due and Nonaccrual Loans (Details) - USD ($)		Mar. 31, 2019		Dec. 31, 2018		Mar. 31, 2018
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		$ 7,488,000		$ 7,480,000
Current		1,743,501,000		1,724,448,000
Total Financing Receivables		1,750,989,000		1,731,928,000
Non-Accrual Loans	[1]	4,568,000		5,156,000
Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		6,929,000		4,748,000
Current		1,466,921,000		1,449,182,000
Total Financing Receivables		1,473,850,000		1,453,930,000
Non-Accrual Loans	[1]	3,621,000		3,585,000
1-4 Family Residential Construction [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,650,000		0
Current		104,684,000		105,676,000
Total Financing Receivables		106,334,000		105,676,000
Non-Accrual Loans	[1]	0		0
Other construction/land [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		28,000		237,000
Current		108,802,000		108,786,000
Total Financing Receivables		108,830,000		109,023,000
Non-Accrual Loans	[1]	75,000		82,000
1-4 Family - Closed-End [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,491,000		1,094,000
Current		231,149,000		235,731,000
Total Financing Receivables		232,640,000		236,825,000
Non-Accrual Loans	[1]	822,000		799,000
Equity Lines [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		391,000		1,528,000
Current		51,252,000		54,792,000
Total Financing Receivables		51,643,000		56,320,000
Non-Accrual Loans	[1]	488,000		408,000
Multi Family Residential [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Current		55,075,000		54,877,000
Total Financing Receivables		55,075,000		54,877,000
Non-Accrual Loans	[1]	0		0
Commercial Real Estate Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,440,000		285,000
Current		319,676,000		301,039,000
Total Financing Receivables		321,116,000		301,324,000
Non-Accrual Loans	[1]	594,000		605,000
Commercial Real Estate Non Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		314,000		49,000
Current		442,788,000		438,295,000
Total Financing Receivables		443,102,000		438,344,000
Non-Accrual Loans	[1]	0		49,000
Farmland [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,615,000		1,555,000
Current		153,495,000		149,986,000
Total Financing Receivables		155,110,000		151,541,000
Non-Accrual Loans	[1]	1,642,000		1,642,000
Agricultural [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Current		52,086,000		49,103,000
Total Financing Receivables		52,086,000		49,103,000
Non-Accrual Loans	[1]	0		0
Commercial And Industrial Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		382,000		2,536,000
Current		125,297,000		125,684,000
Total Financing Receivables		125,679,000		128,220,000
Non-Accrual Loans	[1]	811,000		1,425,000
Mortgage Warehouse Lines [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Current		91,118,000		91,813,000
Total Financing Receivables		91,118,000		91,813,000
Non-Accrual Loans	[1]	0		0
Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		177,000		196,000
Current		8,079,000		8,666,000
Total Financing Receivables		8,256,000		8,862,000
Non-Accrual Loans	[1]	136,000		146,000
30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		4,256,000		5,449,000
30-59 Days Past Due [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		4,132,000		3,787,000
30-59 Days Past Due [Member] | 1-4 Family Residential Construction [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,650,000		0
30-59 Days Past Due [Member] | Other construction/land [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		210,000
30-59 Days Past Due [Member] | 1-4 Family - Closed-End [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		761,000		319,000
30-59 Days Past Due [Member] | Equity Lines [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		67,000		1,471,000
30-59 Days Past Due [Member] | Multi Family Residential [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
30-59 Days Past Due [Member] | Commercial Real Estate Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,340,000		183,000
30-59 Days Past Due [Member] | Commercial Real Estate Non Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		314,000		49,000
30-59 Days Past Due [Member] | Farmland [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		1,555,000
30-59 Days Past Due [Member] | Agricultural [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
30-59 Days Past Due [Member] | Commercial And Industrial Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		26,000		1,567,000
30-59 Days Past Due [Member] | Mortgage Warehouse Lines [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
30-59 Days Past Due [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		98,000		95,000
60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		285,000		128,000
60-89 Days Past Due [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		268,000		0
60-89 Days Past Due [Member] | 1-4 Family Residential Construction [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Other construction/land [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | 1-4 Family - Closed-End [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Equity Lines [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		268,000		0
60-89 Days Past Due [Member] | Multi Family Residential [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Commercial Real Estate Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Commercial Real Estate Non Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Farmland [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Agricultural [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Commercial And Industrial Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		83,000
60-89 Days Past Due [Member] | Mortgage Warehouse Lines [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
60-89 Days Past Due [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		17,000		45,000
90 Days Or More Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		2,947,000	[2]	1,903,000	[3]
90 Days Or More Past Due [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		2,529,000	[2]	961,000	[3]
90 Days Or More Past Due [Member] | 1-4 Family Residential Construction [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0	[2]	0	[3]
90 Days Or More Past Due [Member] | Other construction/land [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		28,000	[2]	27,000	[3]
90 Days Or More Past Due [Member] | 1-4 Family - Closed-End [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due				0		$ 0
90 Days Or More Past Due [Member] | 1-4 Family - Closed-End [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		730,000	[2]	775,000	[3]
90 Days Or More Past Due [Member] | Equity Lines [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		56,000	[2]	57,000	[3]
90 Days Or More Past Due [Member] | Multi Family Residential [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0	[2]	0	[3]
90 Days Or More Past Due [Member] | Commercial Real Estate Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		100,000	[2]	102,000	[3]
90 Days Or More Past Due [Member] | Commercial Real Estate Non Owner Occupied [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0	[2]	0	[3]
90 Days Or More Past Due [Member] | Farmland [Member] | Real Estate Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,615,000	[2]	0	[3]
90 Days Or More Past Due [Member] | Agricultural [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0	[2]	0	[3]
90 Days Or More Past Due [Member] | Commercial And Industrial Loan [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		356,000	[2]	886,000	[3]
90 Days Or More Past Due [Member] | Mortgage Warehouse Lines [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0	[2]	0	[3]
90 Days Or More Past Due [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		$ 62,000	[2]	$ 56,000	[3]

[1] Included in total financing receivables

[2] As of March 31, 2018 there were no loans over 90 days past due and still accruing.

[3] As of December 31, 2018 there were no loans over 90 days past due and still accruing.