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	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	$ 445		$ 513
Collectively evaluated for impairment	23,023		21,234
Acquired with deteriorated credit quality	14
Ending balance	23,482	$ 23,247	21,747	$ 23,290	$ 23,734	$ 24,460
Commercial and Industrial
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	15		135
Collectively evaluated for impairment	5,719		5,174
Ending balance	5,734	5,440	5,309	5,955	5,924	5,135
Construction
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	6,125		4,940
Ending balance	6,125	5,579	4,940	4,471	4,373	5,143
Residential Real Estate | 1-to-4 Family Mortgage
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	24		23
Collectively evaluated for impairment	2,735		3,174
Ending balance	2,759	2,974	3,197	3,495	3,611	4,176
Residential Real Estate | Residential Line of Credit
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	1,028		1,613
Ending balance	1,028	1,445	1,613	1,825	1,944	2,201
Residential Real Estate | Multi-Family Mortgage
Accounts Notes And Loans Receivable [Line Items]
Collectively evaluated for impairment	523		504
Ending balance	523	513	504	611	453	311
Commercial Real Estate | Owner Occupied
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	352		113
Collectively evaluated for impairment	3,656		3,189
Ending balance	4,008	3,983	3,302	3,685	3,764	3,682
Commercial Real Estate | Non-Owner Occupied
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	43		242
Collectively evaluated for impairment	2,434		1,777
Ending balance	2,477	2,452	2,019	2,289	2,634	2,622
Consumer and Other
Accounts Notes And Loans Receivable [Line Items]
Individually evaluated for impairment	11
Collectively evaluated for impairment	803		863
Acquired with deteriorated credit quality	14
Ending balance	$ 828	$ 861	$ 863	$ 959	$ 1,031	$ 1,190