Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Securities, market value	$ 575,404	$ 615,458	$ 580,630
Common stock, par value	$ 1.00	$ 1.00	$ 1.00
Common stock, shares authorized	20,000,000	20,000,000	20,000,000
Common stock, shares issued	15,153,991	15,117,430	15,273,181
Common stock, shares outstanding	15,153,991	15,117,430	15,273,181
Accumulated other comprehensive income, tax	$ 3,746	$ 5,084	$ 5,217
Senior preferred stock
Preferred stock, par value	$ 1.00	$ 1.00	$ 1.00
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued	0	0	0
Cumulative preferred stock
Preferred stock, par value	$ 5.00	$ 5.00	$ 5.00
Preferred stock, shares authorized	900,000	900,000	900,000
Preferred stock, shares issued	0	0	0