Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 12,475	$ 9,261	$ 60,754	$ 49,146
Amortization of prior service cost, net of tax of $(5), $(5), $(15) and $(15), respectively	(14)	(14)	(42)	(42)
Net gain, net of tax of $28, $28, $53 and $55, respectively	(78)	(80)	(234)	(240)
Unrealized gain on commodity contract cash flow hedges, net of tax of $688, $282, $1,945 and $935, respectively	1,803	740	5,094	2,450
Unrealized gain/(loss) on interest rate swap cash flow hedges, net of tax of $2, $(14), $1 and $(14), respectively	14	27	18	(10)
Other comprehensive income (loss)	1,881	833	5,304	2,638
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 14,356	$ 10,094	$ 66,058	$ 51,784