Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Investment securities held to maturity; fair value	$ 138,688	$ 146,990
Common stock, par value
Common stock, shares authorized	70,000,000	70,000,000
Common stock, shares issued	47,353,864	47,222,914