Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets:
Securities available-for-sale at amortized cost	$ 611,178	$ 608,939
Securities held-to-maturity at fair value	858	867
Core deposit intangible, accumulated amortization	$ 8,562	$ 8,483
Shareholders' equity:
Preferred stock, shares authorized (in shares)	300,000	300,000
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	25,000,000	25,000,000
Common stock, shares outstanding (in shares)	17,670,501	17,628,695