Statement of Comprehensive Income (Statement) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net Income (Loss) Attributable to Parent	$ 153,945	$ 127,923	$ 102,700
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	1,754	928	1,487
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax	(26,875)	8,675	(1,511)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax, Total	(28,629)	7,747	(2,998)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	0	2,596	(333)
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, Net of Tax	0	0	19,095
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	(19,537)	25,747	18,227
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax	(19,537)	23,151	37,655
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	492	(244)	(454)
Other Comprehensive Income (Loss), Net of Tax	9,584	15,160	40,199
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total	$ 163,529	$ 143,083	$ 142,899