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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ 949
Other comprehensive income (loss)	$ 762	$ (203)	1,905	$ (1,512)
Ending balance	2,854		2,854
Unrealized Gains and Losses On Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	2,124	1,078	981	16,003
Cumulative effect adjustment for adoption of new accounting standards				(13,616)
Other comprehensive income before reclassifications	762	(203)	1,905	(1,512)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss)	762	(203)	1,905	(1,512)
Ending balance	2,886	875	2,886	875
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	2,092	1,009	949	15,945
Cumulative effect adjustment for adoption of new accounting standards				(13,627)
Other comprehensive income before reclassifications	762	(203)	1,905	(1,512)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Other comprehensive income (loss)	762	(203)	1,905	(1,512)
Ending balance	$ 2,854	$ 806	$ 2,854	$ 806