Shareholders' Equity - Narrative (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended												12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 16, 2019	Dec. 31, 2016
Equity [Abstract]
Stockholders' equity increase														$ 22,200
Shareholders' equity		$ 160,709				$ 138,488				$ 118,105				160,709	$ 138,488	$ 118,105		$ 106,291
Net income		$ 6,120	$ 5,959	$ 5,834	$ 5,740	$ 5,803	$ 5,490	$ 5,397	$ 5,229	$ 2,500	$ 3,757	$ 3,444	$ 3,192	23,653	21,919	12,893
Dividends on common stock														3,255	2,802	2,380
Common stock issued and related tax effects	[1]													1,512	1,595	1,255
Accumulated other comprehensive income														$ 311	$ (328)	$ 46
Total shares repurchased (in shares)																	525
Maximum percentage of outstanding common stock authorized for repurchase																	5.00%

[1] (1) Includes the issuance of common stock under employee benefit plans, which includes nonqualified stock options and restricted stock expense related entries, employee option exercises and the tax benefit of options exercised.