Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Interest bearing deposits, banks	$ 2,885	$ 10,929
Held-to-maturity, Estimated Fair Value	$ 607,032	$ 621,472
Preferred stock, no par value
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 2.0833	$ 2.0833
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	26,667,739	26,633,848
Common stock, shares outstanding	26,664,644	26,629,360
Treasury stock, shares	3,095	4,488