Parent Company Financial Information - Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 30, 2011	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income		$ 22,579	$ 15,249	$ 16,301
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of securities		(81)	(812)	(836)
Net change in other assets		(100)	(379)	(1,390)
Net change in other liabilities		723	284	867
Net cash provided by operating activities		27,502	25,751	16,117
Cash Flows from Investing Activities:
Purchases of securities available for sale		(106,575)	(84,931)	(168,069)
Proceeds from sales of securities			55,903	13,019
Net cash used in investing activities		(39,901)	(147,856)	(175,366)
Cash Flows from Financing Activities:
Common stock dividends paid		(8,702)	(8,384)	(8,266)
Repurchase of common stock		0	0	(1,292)
Proceeds from exercise of stock options		861	113	142
Proceeds from issuance of common stock	$ 619
Net cash provided by financing activities		24,177	121,375	117,119
Net Increase (Decrease) in Cash and Cash Equivalents		11,778	(730)	(42,130)
Cash and Cash Equivalents at Beginning of Period		52,477	53,207	95,337
Cash and Cash Equivalents at End of Period		64,255	52,477	53,207
Parent Company
Cash Flows from Operating Activities:
Net income		22,579	15,249	16,301
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of securities		0	(221)	0
Equity in (undistributed) distributions of subsidiary		(13,112)	(9,942)	(1,320)
Net change in other assets		(194)	83	(57)
Net change in other liabilities		136	(82)	163
Net cash provided by operating activities		9,409	5,087	15,087
Cash Flows from Investing Activities:
Purchases of securities available for sale		0	(373)	(6,588)
Proceeds from sales of securities		0	500	0
Net cash used in investing activities		431	127	(6,588)
Cash Flows from Financing Activities:
Common stock dividends paid		(8,702)	(8,384)	(8,266)
Repurchase of common stock		0	0	(1,292)
Proceeds from exercise of stock options		861	113	142
Net cash provided by financing activities		(7,841)	(8,271)	(9,416)
Net Increase (Decrease) in Cash and Cash Equivalents		1,999	(3,057)	(917)
Cash and Cash Equivalents at Beginning of Period		1,597	4,654	5,571
Cash and Cash Equivalents at End of Period		$ 3,596	$ 1,597	$ 4,654