Consolidated Statement of Stockholders' Equity (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Taxes on unrealized holding losses	$ 3,143	$ 415	$ 2,826
Net Realized Gains On Unrealized Holding Losses	1,940	1,851	2,734
Taxes on pension liabilities adjustments	2,439	836	50
Conversion of class B common stock to class A common stock, shares			12,570
Stock Repurchased During Period, Shares			8,110
Stock option exercised, shares	2,450	9,950
Class A Common Stock
Conversion of class B common stock to class A common stock, shares	17,000	3,150	12,570
Stock Repurchased During Period, Shares			8,110
Stock option exercised, shares	2,450	9,950
Cash dividends paid	$ 0.48	$ 0.48	$ 0.48
Class B Common Stock
Conversion of class B common stock to class A common stock, shares	17,000	3,150	12,570
Cash dividends paid	$ 0.24	$ 0.24	$ 0.24
Additional Paid-In Capital
Stock Repurchased During Period, Shares			8,110
Stock option exercised, shares	2,450	9,950
Retained Earnings | Class A Common Stock
Cash dividends paid	$ 0.48	$ 0.48	$ 0.48
Retained Earnings | Class B Common Stock
Cash dividends paid	$ 0.24	$ 0.24	$ 0.24
Accumulated Other Comprehensive Income (Loss)
Taxes on unrealized holding losses	3,143	415	2,826
Net Realized Gains On Unrealized Holding Losses	1,940	1,851	2,734
Taxes on pension liabilities adjustments	$ 2,439	$ 836	$ 50