CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
CONSOLIDATED BALANCE SHEETS
Securities available-for-sale, cost (in dollars)	$ 7,042,934	$ 5,658,120	$ 5,275,623
Other real estate owned, covered by FDIC loss share (in dollars)	$ 102,848	$ 120,866	$ 110,391
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00	$ 1.00
Common stock, shares authorized	75,000,000	75,000,000	75,000,000
Common stock, shares issued	53,885,886	53,885,886	53,885,886
Treasury shares	1,401,598	1,639,203	1,771,740