Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Securities held to maturity, fair value	$ 316,698	$ 344,618
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 5.00	$ 5.00
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	26,715,797	26,715,797
Common stock, shares outstanding	25,120,412	25,066,068