Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017		Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 7,208		$ 6,647		$ 13,839		$ 13,196
Net Unrealized Securities Holding Gains Arising During the Period	409	[1]	682	[1]	456		3,119	[1]
Reclassification Adjustments for Securities Gains Included in Net Income	0	[1]	(88)	[1]	0	[2]	(88)	[1]
Amortization of Net Retirement Plan Actuarial Loss	72	[1]	102	[1]	181		203	[1]
Accretion of Net Retirement Plan Prior Service Credit	(1)	[1]	(2)	[1]	(3)		(4)	[1]
Other Comprehensive Income	480		694		634		3,230
Comprehensive Income	$ 7,688		$ 7,341		$ 14,473		$ 16,426

[1] All amounts are net of tax. Amounts in parentheses indicate debits.

[2] These accumulated other comprehensive income components are included in the computation of net periodic pension cost.