Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends declared, per shares (in dollars per share)	$ 0.55	$ 0.35
Shares of stock pursuant to dividend reinvestment plan (in shares)	91,487	64,837
Shares of stock pursuant to exercise of stock options (in shares)	8,763	6,729
Net change in fair value of available-for-sale securities, tax	$ 883	$ (1,687)