Accumulated Other Comprehensive Income Balances Of Each Component Of Accumulated Other Comprehensive Income, Net Of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 3,226
Other comprehensive loss	(2,008)	$ (610)
Ending balance	1,218
Unrealized Gains and Losses On Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	3,370	4,470
Other comprehensive income before reclassifications	(2,181)	(592)
Amounts reclassified from accumulated other comprehensive income	0	(18)
Other comprehensive loss	(2,181)	(610)
Ending balance	1,189	3,860
Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(144)	(144)
Other comprehensive income before reclassifications	173	0
Amounts reclassified from accumulated other comprehensive income	0	0
Other comprehensive loss	173	0
Ending balance	29	(144)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	3,226	4,326
Other comprehensive income before reclassifications	(2,008)	(592)
Amounts reclassified from accumulated other comprehensive income	0	(18)
Other comprehensive loss	(2,008)	(610)
Ending balance	$ 1,218	$ 3,716