Accumulated Other Comprehensive Income - Significant amounts reclassified (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain loss on sales of securities		$ 6		$ (1)
Other operating expenses	$ 1,097	1,044	$ 2,191	2,042
Income tax expense	174	587	368	1,130
Net income	1,137	2,098	2,247	4,266
Amount Reclassified from Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	2	(3)	4	5
Net income	2	(3)	4	5
Amount Reclassified from Accumulated Other Comprehensive Income | Unrealized Gains on Available for Sale Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain loss on sales of securities		(6)		1
Income tax expense		1
Net of tax		(5)		1
Amount Reclassified from Accumulated Other Comprehensive Income | Amortization of defined benefit items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense				(1)
Net of tax	2	2	4	4
Amount Reclassified from Accumulated Other Comprehensive Income | Amortization of defined benefit items: Actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses	2	2	5	$ 5
Income tax expense			(1)
Net of tax	$ 2	$ 2	$ 4