Accumulated Other Comprehensive Income Balances Of Each Component Of Accumulated Other Comprehensive Income, Net Of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 949
Other comprehensive income (loss)	$ 341	$ (487)	2,246	$ (1,999)
Ending balance	3,195		3,195
Unrealized Gains and Losses On Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	2,886	875	981	16,003
Cumulative effect adjustment for adoption of new accounting standards				(13,616)
Other comprehensive income before reclassifications	341	(487)	2,246	(1,999)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss)	341	(487)	2,246	(1,999)
Ending balance	3,227	388	3,227	388
Postretirement Benefits Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(32)	(69)	(32)	(58)
Cumulative effect adjustment for adoption of new accounting standards				(11)
Other comprehensive income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Ending balance	(32)	(69)	(32)	(69)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	2,854	806	949	15,945
Cumulative effect adjustment for adoption of new accounting standards				(13,627)
Other comprehensive income before reclassifications	341	(487)	2,246	(1,999)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss)	341	(487)	2,246	(1,999)
Ending balance	$ 3,195	$ 319	$ 3,195	$ 319