Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income (Loss)
Taxes on unrealized holding losses	$ 2,491	$ 3,143	$ 415
Net realized gains on unrealized holding losses	1,843	1,940	1,851
Taxes on pension liabilities adjustments	$ 1,223	$ 2,439	$ 836
Class A Common Stock
Conversion of class B common stock to class A common stock, shares	7,500	17,000	3,150
Stock option exercised, shares	12,262	2,450	9,950
Cash dividends paid	$ 0.48	$ 0.48	$ 0.48
Class B Common Stock
Cash dividends paid	$ 0.24	$ 0.24	$ 0.24