Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 13,813	$ 10,956	$ 48,279	$ 39,886
Amortization of prior service cost, net of tax of $(5), $(5), $(10) and $(10), respectively	(14)	(14)	(28)	(28)
Net gain, net of tax of $28, $28, $53 and $55, respectively	(78)	(80)	(156)	(160)
Unrealized gain on commodity contract cash flow hedges, net of tax of $1,193, $651, $1,257 and $653, respectively	3,126	1,703	3,291	1,710
Unrealized gain/(loss) on interest rate swap cash flow hedges, net of tax of $2, $(14), $1 and $(14), respectively	6	(37)	4	(37)
Other comprehensive income (loss)	3,196	1,732	3,423	1,805
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 17,009	$ 12,688	$ 51,702	$ 41,691