Accumulated Other Comprehensive Income, Reclassification of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less provision for income taxes	$ 941	$ 483
Reclassification adjustment, net of taxes	(14)		$ (6)
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	(14)		$ (6)
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 loss on sale of debt securities	(18)	0
Less provision for income taxes	(4)	0
Reclassification adjustment, net of taxes	$ (14)	$ 0