CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2010	$ 246,997	$ 85,766	$ 161,299	$ 1,350	$ (1,418)
Comprehensive income:
Net income	13,954		13,954
Other comprehensive income (loss), net of tax	2,412			2,412
Comprehensive income	16,366
Common stock cash dividends declared	(5,035)		(5,035)
Treasury shares purchased under deferred directors' plan	0	113			(113)
Treasury shares sold under the deferred directors' plan	0	(440)			440
Stock activity under stock compensation plans, net of taxes	336	336
Stock compensation expense	647	647
Balance at end of period at Jun. 30, 2011	259,311	86,422	170,218	3,762	(1,091)
Balance at Dec. 31, 2011	273,200	87,380	181,903	5,139	(1,222)
Comprehensive income:
Net income	17,445		17,445
Other comprehensive income (loss), net of tax	1,352			1,352
Comprehensive income	18,797
Common stock cash dividends declared	(5,302)		(5,302)
Treasury shares purchased under deferred directors' plan	0	186			(186)
Stock activity under stock compensation plans, net of taxes	185	185
Stock compensation expense	689	689
Balance at end of period at Jun. 30, 2012	$ 287,569	$ 88,440	$ 194,046	$ 6,491	$ (1,408)