CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock Outstanding [Member]	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at at Dec. 31, 2015	$ 524,427		$ 24,296	$ 175,588	$ 325,840	$ (1,297)
Net income	21,460		0	0	21,460	0
Other comprehensive income, net of tax	7,183		0	0	0	7,183
Common stock dividends - $0.52 and $0.48 per share at June 30, 2017 and 2016 respectively.	(11,622)		0	0	(11,622)	0
Stock compensation expense	992		0	992	0	0
Common stock issued pursuant to:
Stock option plan - 27,284 and 28,941 shares at June 30, 2017 and 2016, respectively	422		29	393	0	0
Employee stock purchase plan - 8,565 and 12,471 shares at June 30, 2017 and 2016, respectively	291		12	279
Director's stock purchase plan - 258 shares at June 30, 2016	16		1	15
Restricted stock - 47,064 and 49, 648 shares at June 30, 2017 and 2016, respectively	(417)		49	(466)	0	0
Purchase of treasury shares - 512,459 shares at June 30, 2016	(13,273)	$ (512)		(12,761)	0	0
Balance at at Jun. 30, 2016	529,479		23,875	164,040	335,678	5,886
Balance at at Dec. 31, 2016	533,572		23,901	165,871	350,414	(6,614)
Net income	29,853		0	0	29,853	0
Other comprehensive income, net of tax	2,902		0	0	0	2,902
Common stock dividends - $0.52 and $0.48 per share at June 30, 2017 and 2016 respectively.	(12,561)		0	0	(12,561)	0
Stock compensation expense	1,052		0	1,052	0	0
Common stock issued pursuant to:
Stock option plan - 27,284 and 28,941 shares at June 30, 2017 and 2016, respectively	518		27	491	0	0
Employee stock purchase plan - 8,565 and 12,471 shares at June 30, 2017 and 2016, respectively	299		9	290	0	0
Restricted stock - 47,064 and 49, 648 shares at June 30, 2017 and 2016, respectively	(952)		47	(999)	0	0
Balance at at Jun. 30, 2017	$ 554,683		$ 23,984	$ 166,705	$ 367,706	$ (3,712)