Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Cash and due from banks, interest-bearing amounts	$ 83,701	$ 57,048
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	36,130,480	31,197,365
Common stock, shares outstanding	34,812,723	29,796,397
Treasury stock, shares	1,317,757	1,400,968