Accumulated Other Comprehensive Income (''AOCI'') - Amount Reclassified from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Amount Reclassified from AOCI
Gain on sales of securities	$ 100
Interest income on taxable securities	3,948	$ 4,509
Income tax expense	(868)	(4,507)
Net income	1,861	12,146
Income before income tax	2,729	16,653
Unrealized Gains (Losses) on Available-for-Sale Securities and I/O Strips
Amount Reclassified from AOCI
Net of tax	71
Unrealized Gains (Losses) on Available-for-Sale Securities and I/O Strips | Amount Reclassified from AOCI
Amount Reclassified from AOCI
Gain on sales of securities	100
Income tax expense	(29)
Net income	71
Unamortized Unrealized Gain on Available-for-Sale Securities Reclassified to Held-to-Maturity
Amount Reclassified from AOCI
Net of tax	9	18
Unamortized Unrealized Gain on Available-for-Sale Securities Reclassified to Held-to-Maturity | Amount Reclassified from AOCI
Amount Reclassified from AOCI
Interest income on taxable securities	13	26
Income tax expense	(4)	(8)
Net income	9	18
Defined Benefit Pension Plan Items
Amount Reclassified from AOCI
Net of tax	(49)	(15)
Defined Benefit Pension Plan Items | Amount Reclassified from AOCI
Amount Reclassified from AOCI
Other noninterest expense	(70)	(21)
Income tax benefit	21	6
Net of tax	(49)	(15)
Prior transition obligation | Amount Reclassified from AOCI
Amount Reclassified from AOCI
Other noninterest expense	15	25
Actuarial losses | Amount Reclassified from AOCI
Amount Reclassified from AOCI
Other noninterest expense	(85)	(46)
Accumulated Other Comprehensive Income / (Loss)
Amount Reclassified from AOCI
Net of tax	31	3
Accumulated Other Comprehensive Income / (Loss) | Amount Reclassified from AOCI
Amount Reclassified from AOCI
Net of tax	$ 31	$ 3