Comprehensive Income Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Schedule of Comprehensive Income [Line Items]
Other Comprehensive Income, before Tax	$ (695)		$ 844		$ (3,968)	$ 1,096
Other Comprehensive Income, Tax	176		(364)		1,009	(462)
Net current-period other comprehensive income (loss)	(519)		480		(2,959)	634
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	(853)		666		(4,185)	743
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period, Tax	218		(257)		1,065	(287)
Other comprehensive income or loss before reclassifications	(635)		409	[1]	(3,120)	456
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		[1]	0	[1]	0	0
Net current-period other comprehensive income (loss)	(635)	[1]	409	[1]	(3,120)	456
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Schedule of Comprehensive Income [Line Items]
Other comprehensive income or loss before reclassifications	0	[1]	0	[1]	0	0
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax	103		181		163	359
Reclassification from Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	(28)		(109)		(42)	(178)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	75	[1]	72	[1]	121	181
Net current-period other comprehensive income (loss)	75	[1]	72	[1]	121	181
Accumulated Defined Benefit Plans Adjustment, Net Prior Service
Schedule of Comprehensive Income [Line Items]
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax	55		(3)		54	(6)
Reclassification from Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	(14)		2		(14)	3
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 41		$ (1)		$ 40	$ (3)

[1] All amounts are net of tax.