Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Investment securities, held to maturity fair value	$ 203,896	$ 201,085
Allowance for loan losses	$ 16,474	$ 16,394
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value
Common stock, shares authorized	66,000,000	66,000,000
Common stock, shares issued	25,580,304	25,549,069
Common stock, shares outstanding	25,555,235	25,529,819