Loans and Allowance for Loan Losses - Loan Summary (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]
Total loans	$ 1,867,747		$ 1,777,239
Less: Allowance for loan losses	(9,792)	$ (9,097)	(8,275)	$ (7,156)	$ (7,074)	$ (5,860)
Loans, net	1,857,955		1,768,964
Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	30,471		34,158
Less: Allowance for loan losses	(116)		0
Loans, net	30,355		34,158
All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,837,276		1,743,081
Less: Allowance for loan losses	(9,676)		(8,275)
Loans, net	1,827,600		1,734,806
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	890,462		860,027
Less: Allowance for loan losses	(4,260)	(4,102)	(3,639)	(3,245)	(3,135)	(2,465)
Commercial Real Estate [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	17,880		17,682
Less: Allowance for loan losses	(35)		0
Commercial Real Estate [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	872,582		842,345
Less: Allowance for loan losses	(4,225)		(3,639)
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	405,531		407,254
Less: Allowance for loan losses	(2,270)	(2,189)	(1,789)	(1,598)	(1,528)	(1,596)
Consumer Real Estate [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	7,169		8,712
Less: Allowance for loan losses	(81)		0
Consumer Real Estate [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	398,362		398,542
Less: Allowance for loan losses	(2,189)		(1,789)
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	219,751		187,895
Less: Allowance for loan losses	(1,043)	(946)	(795)	(709)	(744)	(521)
Construction and Land Development [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,629		4,602
Less: Allowance for loan losses	0		0
Construction and Land Development [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	215,122		183,293
Less: Allowance for loan losses	(1,043)		(795)
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	341,207		308,254
Less: Allowance for loan losses	(2,148)	(1,746)	(1,746)	(1,362)	(1,367)	(1,062)
Commercial and Industrial [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	434		2,557
Less: Allowance for loan losses	0		0
Commercial and Industrial [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	340,773		305,697
Less: Allowance for loan losses	(2,148)		(1,746)
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	10,796		13,809
Less: Allowance for loan losses	(71)	$ (114)	(306)	$ (242)	$ (300)	$ (216)
Consumer and Other [Member] | Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	359		605
Less: Allowance for loan losses	0		0
Consumer and Other [Member] | All Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	10,437		13,204
Less: Allowance for loan losses	$ (71)		$ (306)