Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 9,730	$ 7,208	$ 18,261	$ 13,839
Other Comprehensive Income, Net of Tax:
Net Unrealized Securities Holding Gains (Losses) Arising During the Period	(635)	409	(3,120)	456
Amortization of Net Retirement Plan Actuarial Loss	75	72	121	181
Accretion of Net Retirement Plan Prior Service Credit	41	(1)	40	(3)
Other Comprehensive Income (Loss)	(519)	480	(2,959)	634
Comprehensive Income	$ 9,211	$ 7,688	$ 15,302	$ 14,473

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount, after tax, of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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