Comprehensive Income Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Schedule of Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		$ 0	$ 6		$ 0		$ 6	[1]
Other Comprehensive Income, before Tax		(1,095)	172		(5,063)		1,268
Other Comprehensive Income, Tax		278	(107)		1,287		(569)
Net current-period other comprehensive income (loss)		(817)	65		(3,776)		699
Unrealized Gains and Losses on Available for Sale Securities
Schedule of Comprehensive Income [Line Items]
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period Before Tax		(1,203)	6		(5,388)		749
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period, Tax		306	3		1,371		(284)
Other comprehensive income or loss before reclassifications		(897)	9	[1]	(4,017)	[1]	465	[1]
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax			10				10
Reclassification From Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit			(4)				(4)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax			(6)				(6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]		(6)		0		(6)
Net current-period other comprehensive income (loss)	[1]	(897)	3		(4,017)		459
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Schedule of Comprehensive Income [Line Items]
Other comprehensive income or loss before reclassifications	[1]	0	0		0		0
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax		81	179		244		537
Reclassification from Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit		(21)	(115)		(63)		(292)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	60	64		181		245
Net current-period other comprehensive income (loss)	[1]	60	64		181		245
Accumulated Defined Benefit Plans Adjustment, Net Prior Service
Schedule of Comprehensive Income [Line Items]
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax		27	(3)		81		(8)
Reclassification from Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit		(7)	1		(21)		3
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		$ 20	$ (2)		$ 60		$ (5)

[1] All amounts are net of tax.