Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Capital Stock [Member]	Surplus [Member]	Undivided Profits [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2013	$ 98,927	$ 173,144	$ 147,432	$ (13,803)	$ (43,887)	$ 361,813
Net income	0	0	22,819	0	0	22,819
Other comprehensive income (loss), net of tax	0	0	0	11,192	0	11,192
Cash dividend declared	0	0	(12,419)	0	0	(12,419)
Sale of treasury stock	0	(548)	0	0	1,987	1,439
Stock based compensation expense	0	173	0	0	0	173
Balance at Jun. 30, 2014	98,927	172,769	157,832	(2,611)	(41,900)	385,017
Balance at Dec. 31, 2014	98,945	172,353	166,745	(4,509)	(40,090)	393,444
Net income	0	0	21,442	0	0	21,442
Other comprehensive income (loss), net of tax	0	0	0	(1,418)	0	(1,418)
Cash dividend declared	0	0	(12,466)	0	0	(12,466)
Stock options exercised and related tax benefits	19	80	0	0	0	99
Purchase of treasury stock	0	0	0	0	(99)	(99)
Sale of treasury stock	0	(541)	0	0	1,902	1,361
Stock based compensation expense	0	96	0	0	0	96
Balance at Jun. 30, 2015	$ 98,964	$ 171,988	$ 175,721	$ (5,927)	$ (38,287)	$ 402,459