Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Capital Stock [Member]	Surplus [Member]	Undivided Profits [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2015	$ 98,973	$ 171,443	$ 184,009	$ (4,781)	$ (36,334)	$ 413,310
Net income	0	0	10,409	0	0	10,409
Other comprehensive income, net of tax	0	0	0	4,854	0	4,854
Cash dividend declared	0	0	(6,259)	0	0	(6,259)
Sale of treasury stock	0	(386)	0	0	1,041	655
Stock based compensation expense	0	56	0	0	0	56
Balance at Mar. 31, 2016	98,973	171,113	188,159	73	(35,293)	423,025
Balance at Dec. 31, 2016	99,214	171,425	201,517	(6,251)	(33,219)	432,686
Net income	0	0	10,947	0	0	10,947
Other comprehensive income, net of tax	0	0	0	683	0	683
Cash dividend declared	0	0	(6,291)	0	0	(6,291)
Stock options exercised	279	1,224	0	0	0	1,503
Purchase of treasury stock	0	0	0	0	(1,503)	(1,503)
Sale of treasury stock	0	(63)	0	0	696	633
Stock based compensation expense	0	42	0	0	0	42
Balance at Mar. 31, 2017	$ 99,493	$ 172,628	$ 206,173	$ (5,568)	$ (34,026)	$ 438,700