Comprehensive Income Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Before-Tax Amount
Other Comprehensive Income	$ 2,576	$ (695)	$ 5,583	$ (3,968)
Tax (Expense) Benefit
Other Comprehensive Income	(656)	176	(1,420)	1,009
Net of Tax Amount
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period	1,744	(635)
Amortization of Net Retirement Plan	176	116
Other Comprehensive Loss	1,920	(519)	4,163	(2,959)
Unrealized Gains and Losses on Available for Sale Securities
Before-Tax Amount
Net Unrealized Securities Holding Gains on Securities Available-for-Sale Arising During the Period	2,340	(853)	5,128	(4,185)
Tax (Expense) Benefit
Net Unrealized Securities Holding Gains on Securities Available-for-Sale Arising During the Period	(596)	218	(1,304)	1,065
Net of Tax Amount
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period	1,744	(635)	3,824	(3,120)
Amortization of Net Retirement Plan		0	0	0
Other Comprehensive Loss	1,744	(635)	3,824	(3,120)
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Before-Tax Amount
Amortization of Net Retirement Plan	179	103	342	163
Tax (Expense) Benefit
Amortization of Net Retirement Plan	(46)	(28)	(88)	(42)
Net of Tax Amount
Net Unrealized Securities Holding Losses on Securities Available-for-Sale Arising During the Period	0	0	0	0
Amortization of Net Retirement Plan	133	75	254	121
Other Comprehensive Loss	133	75	254	121
Accumulated Defined Benefit Plans Adjustment, Net Prior Service
Before-Tax Amount
Amortization of Net Retirement Plan	57	55	113	54
Tax (Expense) Benefit
Amortization of Net Retirement Plan	(14)	(14)	(28)	(14)
Net of Tax Amount
Amortization of Net Retirement Plan	$ 43	$ 41	$ 85	$ 40