Accumulated Other Comprehensive Income Balances Of Each Component Of Accumulated Other Comprehensive Income, Net Of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 3,100
Other comprehensive income	$ 1,118	$ 762	1,130	$ 1,905
Ending balance	4,230		4,230
Unrealized Gains and Losses On Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	3,176	2,124	3,132	981
Other comprehensive income before reclassifications	1,118	762	814	1,905
Amounts reclassified from accumulated other comprehensive income	0	0	348	0
Other comprehensive income	1,118	762	1,162	1,905
Ending balance	4,294	2,886	4,294	2,886
Postretirement Benefits Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(64)	(32)	(32)	(32)
Other comprehensive income before reclassifications	0	0	(32)	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income	0	0	(32)	0
Ending balance	(64)	(32)	(64)	(32)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	3,112	2,092	3,100	949
Other comprehensive income before reclassifications	1,118	762	782	1,905
Amounts reclassified from accumulated other comprehensive income	0	0	348	0
Other comprehensive income	1,118	762	1,130	1,905
Ending balance	$ 4,230	$ 2,854	$ 4,230	$ 2,854