2. Investment securities, Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Investment securities with continuous unrealized loss position
Less than 12 Months, Fair Value	$ 1,794	$ 13,531
Less than 12 Months, Unrealized Losses	6	151
12 Months or More, Fair Value	46,060	44,420
12 Months or More, Unrealized Losses	969	1,243
Total, Fair Value	47,854	57,951
Total, Unrealized Losses	975	1,394
Mortgage-backed securities
Investment securities with continuous unrealized loss position
Less than 12 Months, Fair Value	1,520	6,932
Less than 12 Months, Unrealized Losses	5	56
12 Months or More, Fair Value	17,948	17,670
12 Months or More, Unrealized Losses	389	502
Total, Fair Value	19,468	24,602
Total, Unrealized Losses	394	558
U.S. Government sponsored enterprises
Investment securities with continuous unrealized loss position
Less than 12 Months, Fair Value	0	1,784
Less than 12 Months, Unrealized Losses	0	69
12 Months or More, Fair Value	26,240	25,172
12 Months or More, Unrealized Losses	569	724
Total, Fair Value	26,240	26,956
Total, Unrealized Losses	569	793
State and political subdivisions
Investment securities with continuous unrealized loss position
Less than 12 Months, Fair Value	274	4,815
Less than 12 Months, Unrealized Losses	1	26
12 Months or More, Fair Value	1,872	1,578
12 Months or More, Unrealized Losses	11	17
Total, Fair Value	2,146	6,393
Total, Unrealized Losses	$ 12	$ 43