Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investment Securities:
Available for sale securities, pledged	$ 733,496	$ 736,183
Stockholders' Equity:
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 5	$ 5
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	91,729,235	91,729,235
Treasury stock, shares	870,391	196,922