Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Cash and due from banks, interest-bearing amounts	$ 87,201	$ 41,639
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	36,130,480
Common stock, shares outstanding (in shares)	34,913,023	34,810,374
Treasury stock, shares (in shares)	1,217,457	1,320,106