Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
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	29,230,734	24,230,392	24,177,833
Common stock, shares outstanding	24,230,734	24,230,392	24,177,833
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 6,217	$ 6,250	$ 8,280
Loans:
Non-covered	7,868,840	6,643,326	6,129,228
Other real estate owned
Other real estate owned, covered (in dollars)	0	0	4,222
Other real estate owned, non-covered (in dollars)	20,007	18,316	21,731
Acquired credit impaired loans
Loans:
Covered loans	0	0	93,836
Non-covered	627,340	602,546	598,601
Acquired non-credit impaired loans
Loans:
Covered loans	0	0	7,733
Non-covered	$ 1,715,642	$ 836,699	$ 991,505