CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2012	$ 233,815	$ 49,667	$ 181,151	$ 2,997
Beginning Balance (in shares) at Dec. 31, 2012		7,622,750
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,359		18,359
Other comprehensive loss, net of tax	(14,284)			(14,284)
Stock-based compensation expense	340	340
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		23,914
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)	258	258
Cash dividends declared ($0.81 and $0.81 per share)	(6,206)		(6,206)
Ending Balance at Sep. 30, 2013	232,282	50,265	193,304	(11,287)
Ending Balance (in shares) at Sep. 30, 2013		7,646,664
Beginning Balance at Dec. 31, 2013	231,096	47,783	195,660	(12,347)
Beginning Balance (in shares) at Dec. 31, 2013		7,579,913
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,482		18,482
Other comprehensive loss, net of tax	2,896			2,896
Stock-based compensation expense	453	453
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit		23,037
Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares)	157	157
Common stock repurchased (in shares)		(181,355)
Common stock repurchased	(7,155)	(7,155)
Cash dividends declared ($0.81 and $0.81 per share)	(6,017)		(6,017)
Ending Balance at Sep. 30, 2014	$ 239,912	$ 41,238	$ 208,125	$ (9,451)
Ending Balance (in shares) at Sep. 30, 2014		7,421,595