CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED BALANCE SHEETS
Securities available-for-sale, cost (in dollars)	$ 7,445,999	$ 5,658,120
Securities held-to-maturity, fair value (in dollars)	473,903
Other real estate owned, covered by FDIC loss share (in dollars)	$ 98,550	$ 120,866
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	53,885,886	53,885,886
Treasury shares	1,386,705	1,639,203