Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 15,555	$ 16,553	$ 17,664
Other real estate owned
Other real estate owned, covered (in dollars)	34,244	34,257	61,788
Other real estate owned, non-covered (in dollars)	36,446	32,248	21,381
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	0	0
Preferred stock, shares outstanding	0	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	17,017,904	16,937,464	14,052,177
Common stock, shares outstanding	17,017,904	16,937,464	14,052,177
Acquired loans
Loans:
Covered loans	257,066	282,728	363,051
Non-covered loans	$ 738,189	$ 792,014	$ 6,093