Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Assets
Available-for-sale securities, amortized cost	$ 1,066,255	$ 903,556
Held-to-maturity securities, fair value	$ 200,742	$ 233,524
Stockholders' Equity
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A Common Stock
Stockholders' Equity
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	3,543,717	3,528,867
Class B Common Stock
Stockholders' Equity
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized	5,000,000	5,000,000
Common stock, shares issued	1,996,880	2,011,380