Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Investment securities - held-to-maturity, at amortized cost (fair value)	$ 517,427	$ 625,643	$ 770,688
Common stock, stated value	$ 1	$ 1	$ 1
Common stock, shares authorized	150,000	150,000	150,000
Common stock, shares issued	94,752	87,183	87,172
Common stock, shares outstanding	94,752	87,183	87,172
Preferred Stock, Series A [Member]
Preferred stock, shares authorized	1,000	1,000	1,000
Preferred stock, shares issued	0	0	0
Preferred stock, shares outstanding	0	0	0