Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Class A Common Stock	Class A Common Stock Retained Earnings	Class B Common Stock	Class B Common Stock Retained Earnings
Beginning balance at Dec. 31, 2010	$ 145,025	$ 11,537	$ 131,526	$ (3,578)	$ 3,529		$ 2,011
Net income	12,504		12,504
Unrealized holding losses arising during period, net of $2,098 for 2011 and 2,651 for 2012 in taxes and $362 for 2011 and 1,119 for 2012 in realized net gains	6,876			6,876
Pension liability adjustment, net of $126 for 2011 and 216 for 2012 in taxes	285			285
Comprehensive income
Conversion of class B common stock to class A common stock					17		(17)
Stock options exercised, 350 for 2011 and 5,987 for 2012 shares	6	5			1
Cash dividends paid, Class A and Class B common stock					(1,274)	(1,274)	(361)	(361)
Ending balance at Sep. 30, 2011	163,061	11,542	142,395	3,583	3,547		1,994
Beginning balance at Dec. 31, 2011	160,649	11,587	146,039	(2,519)	3,548		1,994
Net income	14,261		14,261
Unrealized holding losses arising during period, net of $2,098 for 2011 and 2,651 for 2012 in taxes and $362 for 2011 and 1,119 for 2012 in realized net gains	4,217			4,217
Pension liability adjustment, net of $126 for 2011 and 216 for 2012 in taxes	487			487
Comprehensive income
Conversion of class B common stock to class A common stock					8		(8)
Stock options exercised, 350 for 2011 and 5,987 for 2012 shares	137	131			6
Cash dividends paid, Class A and Class B common stock					(1,279)	(1,279)	(360)	(360)
Ending balance at Sep. 30, 2012	$ 178,112	$ 11,718	$ 158,661	$ 2,185	$ 3,562		$ 1,986