CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
CONSOLIDATED BALANCE SHEETS
Securities available-for-sale, cost (in dollars)	$ 9,057,238	$ 7,445,999
Securities held-to-maturity, fair value (in dollars)	1,446,599	473,903
Other real estate owned, covered by FDIC loss share (in dollars)	$ 58,276	$ 98,550
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	175,000
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	669,454	1,386,705