Loans and Allowance for Loan Losses - ALL by Loan Classification (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 9,792	$ 9,097	$ 8,275	$ 7,156	$ 7,074	$ 5,860
All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	9,676		8,275
Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	116		0
Performing [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	9,047		7,741
Impaired Loans [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	629		534
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	4,260	4,102	3,639	3,245	3,135	2,465
Commercial Real Estate [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	4,225		3,639
Commercial Real Estate [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	35		0
Commercial Real Estate [Member] | Performing [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	4,225		3,639
Commercial Real Estate [Member] | Impaired Loans [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0		0
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	2,270	2,189	1,789	1,598	1,528	1,596
Consumer Real Estate [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	2,189		1,789
Consumer Real Estate [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	81		0
Consumer Real Estate [Member] | Performing [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,983		1,763
Consumer Real Estate [Member] | Impaired Loans [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	206		26
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,043	946	795	709	744	521
Construction and Land Development [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,043		795
Construction and Land Development [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0		0
Construction and Land Development [Member] | Performing [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,043		795
Construction and Land Development [Member] | Impaired Loans [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0		0
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	2,148	1,746	1,746	1,362	1,367	1,062
Commercial and Industrial [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	2,148		1,746
Commercial and Industrial [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0		0
Commercial and Industrial [Member] | Performing [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,725		1,304
Commercial and Industrial [Member] | Impaired Loans [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	423		442
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	71	$ 114	306	$ 242	$ 300	$ 216
Consumer and Other [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	71		306
Consumer and Other [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0		0
Consumer and Other [Member] | Performing [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	71		240
Consumer and Other [Member] | Impaired Loans [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 0		$ 66