Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balances (in shares) at Dec. 31, 2015		13,278,824
Beginning Balance at Dec. 31, 2015	$ 252,348	$ 13,279	$ 110,145	$ 125,112	$ 3,812
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	35,184			35,184
Other Comprehensive Income (Loss)	(10,216)				(10,216)
Cash Dividends ($.60, $.52 and $.48 in 2018, 2017 and 2016, respectively)	(10,630)			(10,630)
Issuance of Common Stock for:
Exercise of Stock Options (in shares)		4,166
Exercise of Stock Options	55	$ 4	51
Acquisitions (in shares)		1,942,429
Acquisitions	61,919	$ 1,942	59,977
Restricted Share Grants (in shares)		36,012
Restricted Share Grants	1,407	$ 36	1,371
Income Tax Benefit From Restricted Share Vesting	200		200
Ending Balances (in shares) at Dec. 31, 2016		15,261,431
Ending Balance at Dec. 31, 2016	330,267	$ 15,261	171,744	149,666	(6,404)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	40,676			40,676
Other Comprehensive Income (Loss)	4,253				4,253
Reclass Upon Adoption of ASU 2018-02	0			469	(469)
Cash Dividends ($.60, $.52 and $.48 in 2018, 2017 and 2016, respectively)	(11,842)			(11,842)
Issuance of Common Stock for:
3-for-2 Stock Split (in shares)		7,642,726
3-for-2 Stock Split	(29)	$ 7,643	(7,672)
Restricted Share Grants (in shares)		30,246
Restricted Share Grants	1,246	$ 30	1,216
Income Tax Benefit From Restricted Share Vesting	0		0
Ending Balances (in shares) at Dec. 31, 2017		22,934,403
Ending Balance at Dec. 31, 2017	364,571	$ 22,934	165,288	178,969	(2,620)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	46,529			46,529
Other Comprehensive Income (Loss)	(4,478)				(4,478)
Cash Dividends ($.60, $.52 and $.48 in 2018, 2017 and 2016, respectively)	(14,074)			(14,074)
Issuance of Common Stock for:
Acquisitions (in shares)		1,987,698
Acquisitions	64,737	$ 1,988	62,749
Restricted Share Grants (in shares)		45,357
Restricted Share Grants	1,355	$ 45	1,310
Income Tax Benefit From Restricted Share Vesting	0		0
Ending Balances (in shares) at Dec. 31, 2018		24,967,458
Ending Balance at Dec. 31, 2018	$ 458,640	$ 24,967	$ 229,347	$ 211,424	$ (7,098)