Loans and Allowance for Loan Losses - Allocation of Allowance for Loan Losses by Loan Category Broken Out Between Loans Individually Evaluated for Impairment and Collectively Evaluated for Impairment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	$ 185		$ 191
Collectively evaluated for impairment	25,479		23,850
Acquired with deteriorated credit quality	683
Ending balance	26,347	$ 24,406	24,041	$ 23,247	$ 22,898	$ 21,747
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	49		20
Collectively evaluated for impairment	4,685		4,441
Acquired with deteriorated credit quality	13
Ending balance	4,747	4,578	4,461	5,440	5,402	5,309
Construction
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	8,998		7,135
Acquired with deteriorated credit quality	25
Ending balance	9,023	7,866	7,135	5,579	5,598	4,940
Residential Real Estate | 1-to-4 Family Mortgage
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	12		18
Collectively evaluated for impairment	3,227		3,179
Acquired with deteriorated credit quality	139
Ending balance	3,378	3,122	3,197	2,974	2,896	3,197
Residential Real Estate | Residential Line of Credit
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	795		944
Ending balance	795	1,165	944	1,445	1,514	1,613
Residential Real Estate | Multi-Family Mortgage
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	391		434
Ending balance	391	449	434	513	508	504
Commercial Real Estate | Owner Occupied
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	124		120
Collectively evaluated for impairment	3,082		3,438
Acquired with deteriorated credit quality	84
Ending balance	3,290	3,014	3,558	3,983	3,387	3,302
Commercial Real Estate | Non-Owner Occupied
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment			33
Collectively evaluated for impairment	2,894		2,784
Acquired with deteriorated credit quality	378
Ending balance	3,272	2,753	2,817	2,452	2,660	2,019
Consumer and Other
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	1,407		1,495
Acquired with deteriorated credit quality	44
Ending balance	$ 1,451	$ 1,459	$ 1,495	$ 861	$ 933	$ 863