Accumulated Other Comprehensive Income, Reclassification of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less provision for income taxes	$ 847	$ 1,040	$ 1,816	$ 3,255
Reclassification adjustment, net of taxes			(6)		$ 152
Unrealized Gains and Losses on Available-for-Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment, net of taxes			(6)		$ 152
Unrealized Gains and Losses on Available-for-Sale Securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of debt securities	(7)	78	(8)	218
Less provision for income taxes	(2)	27	(2)	75
Reclassification adjustment, net of taxes	$ (5)	$ 51	$ (6)	$ 143