Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 12,992	$ 16,553	$ 17,750
Other real estate owned
Other real estate owned, covered (in dollars)	40,543	34,257	47,063
Other real estate owned, non-covered (in dollars)	35,330	32,248	27,484
Shareholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued	65,000	0	0
Preferred stock, shares outstanding	65,000	0	0
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50	$ 2.50
Common stock, shares authorized	40,000,000	40,000,000	40,000,000
Common stock, shares issued	24,066,545	16,937,464	15,114,185
Common stock, shares outstanding	24,066,545	16,937,464	15,114,185
Acquired loans
Loans:
Covered loans	361,540	282,728	309,034
Non-covered loans	$ 2,651,563	$ 792,014	$ 211,957