Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 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	24,177,833	24,162,657	24,156,759
Common stock, shares outstanding	24,177,833	24,162,657	24,156,759
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 8,280	$ 9,723	$ 10,232
Other real estate owned
Other real estate owned, covered (in dollars)	4,222	5,751	12,026
Other real estate owned, non-covered (in dollars)	21,731	24,803	24,070
Acquired credit impaired loans
Loans:
Covered loans	93,836	98,459	172,870
Non-covered	598,601	635,411	693,634
Acquired non-cedit impaired loans
Loans:
Covered loans	7,733	8,047	8,591
Non-covered	$ 991,505	$ 1,041,491	$ 1,238,758