Comprehensive Income Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule of Comprehensive Income [Line Items]
Other comprehensive income or loss before reclassifications	$ 2,080	$ (2,485)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	163	45
Other Comprehensive Income, before Tax	3,007	(3,273)
Other Comprehensive Income, Tax	(764)	833
Net current-period other comprehensive income (loss)	2,243	(2,440)
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	2,788	(3,332)
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period, Tax	(708)	847
Other comprehensive income or loss before reclassifications	2,080	(2,485)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0
Net current-period other comprehensive income (loss)	2,080	(2,485)
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Schedule of Comprehensive Income [Line Items]
Other comprehensive income or loss before reclassifications	0	0
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax	163	60
Reclassification from Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	(42)	(14)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	121	46
Net current-period other comprehensive income (loss)	121	46
Accumulated Defined Benefit Plans Adjustment, Net Prior Service
Schedule of Comprehensive Income [Line Items]
Reclassification From Accumulated Other Comprehensive Income Current Period Before Tax	56	(1)
Reclassification from Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	(14)	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 42	$ (1)