Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Cash and due from banks, interest-bearing amounts	$ 41,639	$ 57,048
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	36,130,480	31,197,365
Common stock, shares outstanding (in shares)	34,810,374	29,796,397
Treasury stock, shares (in shares)	1,320,106	1,400,968