Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 46,529	$ 40,676	$ 35,184
Unrealized Gains (Losses) on Securities:
Unrealized Holding Gain (Loss) Arising During the Period	(4,936)	7,364	(13,830)
Reclassification Adjustment for Gains Included in Net Income	(706)	(596)	(1,979)
Tax Effect	1,218	(2,377)	5,607
Net of Tax	(4,424)	4,391	(10,202)
Postretirement Benefit Obligation:
Net (Loss) Arising During the Period	(73)	(226)	(24)
Reclassification Adjustment for Amortization of Prior Service Cost and Net Loss Included in Net Periodic Pension Cost	32	8	6
Tax Effect	(13)	80	4
Net of Tax	(54)	(138)	(14)
Total Other Comprehensive Income (Loss)	(4,478)	4,253	(10,216)
COMPREHENSIVE INCOME	$ 42,051	$ 44,929	$ 24,968