Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 11,019	$ 12,891	$ 12,992
Other real estate owned
Other real estate owned, covered (in dollars)	18,961	27,520	40,543
Other real estate owned, non-covered (in dollars)	32,289	37,398	35,330
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	0	65,000	65,000
Preferred stock, shares outstanding	0	65,000	65,000
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	24,135,220	24,104,124	24,066,545
Common stock, shares outstanding	24,135,220	24,104,124	24,066,545
Credit impaired | Acquired loans
Loans:
Covered loans	197,944	289,123	321,969
Non-covered	782,548	931,515	994,659
Non-credit impaired | Acquired loans
Loans:
Covered loans	9,459	7,824	8,430
Non-covered	$ 1,367,884	$ 1,593,111	$ 1,656,904