Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Shareholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	24,230,392	24,162,657
Common stock, shares outstanding	24,230,392	24,162,657
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 6,250	$ 9,723
Loans:
Non-covered	6,643,326	5,970,044
Other real estate owned
Other real estate owned, covered (in dollars)	0	5,751
Other real estate owned, non-covered (in dollars)	18,316	24,803
Acquired credit impaired loans
Loans:
Covered loans	0	98,459
Non-covered	602,546	635,411
Acquired non-credit impaired loans
Loans:
Covered loans	0	8,047
Non-covered	$ 836,699	$ 1,041,491