CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Tax effect on unrealized holding gains (losses) on securities arising during the period	$ 3,100	$ (1,500)	$ (13)
Income tax expense on reclassification adjustment for net gain on sale of securities included in net income	$ 936	$ 757	$ 119