Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Securities, fair value	$ 565,708	$ 562,815	$ 574,230
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	15,228,277	15,242,308	15,145,280
Common stock, shares outstanding	15,228,277	15,242,308	15,145,280
Accumulated other comprehensive income, tax	$ 3,169	$ 3,400	$ 4,043
Senior preferred stock [Member]
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
Cumulative preferred stock [Member]
Preferred stock, par value	$ 5.00	$ 5.00	$ 5.00
Preferred stock, shares authorized	900,000	900,000	900,000
Preferred stock, shares issued