Investment Securities - Gross Gains on Sales and Redemptions of Available for Sale Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Sales and Redemptions of Available for Sale Securities:
Gross gains	$ 1,122	$ 567	$ 2,731	$ 1,165
Gross losses