Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]		Accumulated Other Comprehensive (Loss) Income [Member]		Treasury Stock [Member]
Beginning balance at Dec. 31, 2015	$ 361,574	$ 110,271	$ 121,280	$ 193,446		$ (16,708)		$ (46,715)
Beginning balance, shares at Dec. 31, 2015		19,530,930
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	19,505	$ 0	0	19,505		0		0
Other comprehensive loss, net of income tax (benefit)	(2,746)	0	0	0		(2,746)		0
Cash dividends declared ($0.80 per share)	(18,435)	$ 0	0	(18,435)		0		0
Stock issued under dividend reinvestment and employee stock purchase plans, shares		115,269
Stock issued under dividend reinvestment and employee stock purchase plans	2,472	$ 0	59	0		0		2,413
Issuance of common stock, acquisitions, shares		6,857,529
Issuance of common stock, acquisitions	144,146	$ 34,288	109,858	0		0		0
Exercise of stock options, shares		261,050
Exercise of stock options	4,968	$ 0	59	0		0		4,909
Stock-based compensation	2,084	$ 0	2,084	0		0		0
Purchases of treasury stock, shares		(328,271)
Purchases of treasury stock	(8,359)	$ 0	0	0		0		(8,359)
Restricted stock awards granted, net of cancellations, shares		152,846
Restricted stock awards granted, net of cancellations	0	$ 0	(2,846)	0		0		2,846
Ending balance at Dec. 31, 2016	505,209	$ 144,559	230,494	194,516		(19,454)		(44,906)
Ending balance, shares at Dec. 31, 2016		26,589,353
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,094	$ 0	0	44,094		0		0
Other comprehensive loss, net of income tax (benefit)	1,683	0	0	0		1,683		0
Cash dividends declared ($0.80 per share)	(21,849)	$ 0	0	(21,849)		0		0
Stock issued under dividend reinvestment and employee stock purchase plans, shares		82,694
Stock issued under dividend reinvestment and employee stock purchase plans	2,413	$ 0	181	0		0		2,232
Issuance of common stock, public offering, shares		2,645,000
Issuance of common stock, public offering	70,501	$ 13,225	57,276	0		0		0
Exercise of stock options, shares		92,370
Exercise of stock options	1,676	$ 0	(119)	0		0		1,795
Stock-based compensation	3,166	$ 0	3,166	0		0		0
Purchases of treasury stock, shares		(119,798)
Purchases of treasury stock	(3,519)	$ 0	0	0		0		(3,519)
Restricted stock awards granted, net of cancellations, shares		45,240
Restricted stock awards granted, net of cancellations	0	$ 0	(865)	0		0		865
Ending balance at Dec. 31, 2017	603,374	$ 157,784	290,133	216,761		(17,771)		(43,533)
Ending balance, shares at Dec. 31, 2017		29,334,859
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-01 [Member]	0	$ 0	0	433	[1]	(433)	[1],[2]	0
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02 [Member]	0	0	0	3,921	[1]	(3,921)	[1],[2]	0
Net income	50,543	0	0	50,543		0		0
Other comprehensive loss, net of income tax (benefit)	(6,291)	0	0	0		(6,291)		0
Cash dividends declared ($0.80 per share)	(23,492)	$ 0	0	(23,492)		0		0
Stock issued under dividend reinvestment and employee stock purchase plans, shares		84,466
Stock issued under dividend reinvestment and employee stock purchase plans	$ 2,295	$ 0	152	1		0		2,142
Exercise of stock options, shares	59,750	59,750
Exercise of stock options	$ 1,131	$ 0	(43)	0		0		1,174
Stock-based compensation	2,557	$ 0	2,557	0		0		0
Purchases of treasury stock, shares		(233,977)
Purchases of treasury stock	(5,984)	$ 0	0	0		0		(5,984)
Restricted stock awards granted, net of cancellations, shares		25,754
Restricted stock awards granted, net of cancellations	0	$ 0	(398)	0		0		398
Ending balance at Dec. 31, 2018	$ 624,133	$ 157,784	$ 292,401	$ 248,167		$ (28,416)		$ (45,803)
Ending balance, shares at Dec. 31, 2018	29,270,852	29,270,852

[1] (1) See Note 1, "Summary of Significant Accounting Policies - Accounting Pronouncements Adopted in 2018" for additional information.

[2] (1) See Note 1, "Summary of Significant Accounting Policies - Accounting Pronouncements Adopted in 2018" for additional information.