Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 34,466	$ 28,930
Amortization of prior service cost, net of tax of $(5) and $(5), respectively	(14)	(14)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	(77)	(80)
Unrealized gain on commodity contract cash flow hedges, net of tax of $63 and $2, respectively	166	7
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent	(2)
Other comprehensive income (loss)	227	73
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 34,693	$ 29,003