Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock Outstanding	Common Stock	Value of Shares Held in Rabbi Trust at Cost	Deferred Compensation and Other Retirement Benefit Obligations	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance March 31, 2016 at Dec. 31, 2014		23,998,738
Balance March 31, 2015 at Dec. 31, 2014	$ 640,527		$ 237	$ (3,666)	$ 3,666	$ 311,978	$ 330,444	$ (2,132)
Net income	9,460						9,460
Other comprehensive income	1,719							1,719
Common dividend declared ($0.29 per share)	(6,800)						(6,800)
Common stock issued for acquisition		2,052,137
Common stock issued for acquisition	86,415		21			86,394
Proceeds from exercise of stock options		23,436
Proceeds from exercise of stock options	321		0			321
Tax benefit related to equity award activity	337					337
Stock based compensation	739					739
Restricted stock awards issued, net of awards surrendered		33,491
Restricted stock awards issued, net of awards surrendered	(635)		1			(636)
Shares issued under direct stock purchase plan		15,774
Shares issued under direct stock purchase plan	638					638
Deferred compensation and other retirement benefit obligations				(34)	34
Increase (Decrease) in Deferred Compensation	0
Tax benefit related to deferred compensation distributions	165					165
Balance December 31, 2015 at Mar. 31, 2015	732,886		259	(3,700)	3,700	399,936	333,104	(413)
Balance December 31, 2014 at Mar. 31, 2015		26,123,576
Balance March 31, 2016 at Dec. 31, 2015		26,236,352
Balance March 31, 2015 at Dec. 31, 2015	771,463		260	(3,958)	3,958	405,486	368,169	(2,452)
Net income	18,611						18,611
Other comprehensive income	4,264							4,264
Common dividend declared ($0.29 per share)	(7,627)						(7,627)
Common stock issued for acquisition	0
Proceeds from exercise of stock options		5,000
Proceeds from exercise of stock options	149					149
Tax benefit related to equity award activity	235					235
Stock based compensation	865					865
Restricted stock awards issued, net of awards surrendered		36,887
Restricted stock awards issued, net of awards surrendered	(671)		1			(672)
Shares issued under direct stock purchase plan		15,326
Shares issued under direct stock purchase plan	679					679
Deferred compensation and other retirement benefit obligations				(73)	73
Tax benefit related to deferred compensation distributions	179					179
Balance December 31, 2015 at Mar. 31, 2016	$ 788,147		$ 261	$ (4,031)	$ 4,031	$ 406,921	$ 379,153	$ 1,812
Balance December 31, 2014 at Mar. 31, 2016		26,293,565