Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 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	24,195,226	24,162,657	24,197,531
Common stock, shares outstanding	24,195,226	24,162,657	24,197,531
Investment securities:
Securities held to maturity, fair value (in dollars)	$ 8,231	$ 9,723	$ 10,114
Other real estate owned
Other real estate owned, covered (in dollars)	0	5,751	8,172
Other real estate owned, non-covered (in dollars)	22,427	24,803	26,870
Acquired credit impaired loans
Loans:
Covered loans	0	98,459	113,158
Non-covered	658,835	635,411	710,823
Acquired non-credit impaired loans
Loans:
Covered loans	0	8,047	8,059
Non-covered	$ 941,886	$ 1,041,491	$ 1,163,613