Investment Securities, Proceeds From Sales (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Proceeds from sales and calls of securities [Abstract]
Gross proceeds	$ 7,831	$ 105,941	$ 61,335
Gross gains	143	250	275
Gross losses	$ 12	$ 534	$ 0