Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Dec. 31, 2009	$ 8,667	$ 113,901	$ (492)	$ 122,076
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	15,569	0	15,569
Other comprehensive loss, net of tax	0	0	(2,149)	(2,149)
Cash dividend	0	(6,309)	0	(6,309)
Balance at Dec. 31, 2010	8,667	123,161	(2,641)	129,187
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	17,638	0	17,638
Other comprehensive loss, net of tax	0	0	1,320	1,320
Cash dividend	0	(6,938)	0	(6,938)
Exercise of stock options	8	84	0	92
Balance at Dec. 31, 2011	8,675	133,945	(1,321)	141,299
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	0	17,747	0	17,747
Other comprehensive loss, net of tax	0	0	(1,417)	(1,417)
Cash dividend	0	(7,639)	0	(7,639)
Exercise of stock options	10	109	0	119
Balance at Dec. 31, 2012	$ 8,685	$ 144,162	$ (2,738)	$ 150,109