Accumulated Other Comprehensive Income Balances Of Each Component Of Accumulated Other Comprehensive Income, Net Of Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance at January 1	$ 3,100	$ 949
Other comprehensive income (loss) before reclassifications	879	2,151
Amounts reclassified from accumulated other comprehensive income	347	0
Net current-period other comprehensive income (loss)	1,226	2,151
Ending balance	4,326	3,100
Unrealized Gains and Losses On Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance at January 1	3,132	981
Other comprehensive income (loss) before reclassifications	991	2,151
Amounts reclassified from accumulated other comprehensive income	347	0
Net current-period other comprehensive income (loss)	1,338	2,151
Ending balance	4,470	3,132
Postretirement Benefits Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance at January 1	(32)	(32)
Other comprehensive income (loss) before reclassifications	(112)	0
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income (loss)	(112)	0
Ending balance	$ (144)	$ (32)