Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
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	24,209,122	24,162,657	24,211,793
Common stock, shares outstanding	24,209,122	24,162,657	24,211,793
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 7,076	$ 9,723	$ 9,758
Loans:
Non-covered	6,489,068	5,970,044	5,835,646
Other real estate owned
Other real estate owned, covered (in dollars)	0	5,751	5,465
Other real estate owned, non-covered (in dollars)	22,211	24,803	25,913
Acquired credit impaired loans
Loans:
Covered loans	0	98,459	103,329
Non-covered	632,617	635,411	665,277
Acquired non-credit impaired loans
Loans:
Covered loans	0	8,047	7,990
Non-covered	$ 885,657	$ 1,041,491	$ 1,099,450